All good rt325, no worries here.  Yes the later plates are slotted, and they do fit a rt3 motor for sure.  So it should fit a dt1 as well.  As for a functional cdi setup that vintage, I think probably harder to deal with than the points...

Yes all those flywheel mags up to the later DT400 or very last DT250 with the good cdi stator will all fit.
Had an RT2MX small rotor cdi on one race kitted DT1 & worked perfect.
No good for the road of course.

Also wanted to add, in case you didn't know.  The 1970-73 dt 250's and rt 360's shared the same pipe.  The dt1m/mx and rt1m/mx shared the same pipe.  Same with the dt2mx and rt2mx.  Pretty sure the mx250/360 followed suit but can't say for sure on them.  Not getting into what actually is perfect or right, but alot of those aftermarket pipes from back in the day were marked for both the 250 and 360.  I've always wanted to try a bassanni, but I told myself I'd suffice with an rt1mx pipe.  Lol.  I actually had my eyes set on one not too long ago, on ebay I believe.

One more thing, and I'm outta here.  I just quickly glanced at the wanted/for sale boards, and there are some aftermarket options there.  Believe dvm had some pipes for sale, and I saw mention of a dt1 motor with a webco head.  Parts are out there if want em.

Hey guys, thanks for the insight, suggestions and warnings. I'll look at the three main areas, carb, pipe and head/squish band. I will try the carb from DT2MX first, have it on hand. I've seen aftermarket/Bassani pipes available, may try that next.
Any machinist recommendations in N. California for the cylinder head modification? It's been 20 years since having that kind of work done and that guy long retired. Thanks again

Racerclam (??) or Bill Bune in Minnesota.
I can get the addresses later on today .

I often wonder if it's the bizarre way the Japanese decided to measure the compression ratio in two strokes that drives the desire to "raise the compression"? 

If the compression ratio is measured in the conventional way (using the piston displacement from BDC) most of these engines already have compression ratios of over 10:1...  some approach 12:1.  Stock. 

In my opinion and experience, the only time to consider raising the compression from stock is if the exhaust port was raised substantially so less head volume is needed to restore the "lost" compression.  Plus stock heads don't have a lot of beam strength and removing metal doesn't help.  It might be more beneficial to remove a few thousandths from the top of the cylinder rather than the head... that helps with the squish and doesn't weaken the head. In most stock engines I've seen, the piston is below being flush with top of cylinder at TDC... sometimes as much as 0.050".

P.S. When modifying a two stroke, more power often requires LESS compression and LESS timing advance.  (For example, a friend of mine has a 100cc Kawasaki Land Speed record holder...  he finally exceeded 100 mph at El Mirage when they lowered the compression and backed off on the timing.)

I respectfully would argue the other side of things, lightly though.  2 strokes don't count the compression, until after the exhaust port is closed.  It's almost opposite of how we figure a 4 stroke engine.  Static on 2 strokes is after port close.  Static on 4 stroke is the whole cylinder stroke.  4 stroke engines can have a high compression ratio (10 or 11 to 1, even higher) and still run on pump gas.  The camshaft bleeding off compression is a big part of it working right, similar to the exhaust port bleeding compression on a 2 stroke.  The head/chamber design plays a big role in making that possible.  Anyway, I tried more compression years ago on stock rt3 cylinder.  It was an improvement, definitely in the torque department.  It was not like the entire rt1mx top end, but an improvement nonetheless.  But I think more could be gained by setting the squish band properly, in a modern fashion.  Someone must know the ins and outs of that trade?  Compression is very low on these motors stock, I truly believe there is decent power to be had with a modernized combustion chamber.

My best argument to this though, hp is not necessarily the desired output we are looking for on these motors.  My case in point:  i downgraded from an rt2mx top end, to a rt1mx top end.  Its no dispute the rt2mx makes way more power.  But if it's peaky at higher rpm, and doggy at lower rpm, it makes it very difficult to manage.  So the less hp is superior imo.  In the case of just adding compression to one of these old enduro motors, I don't think hp loss will be on the table.  Especially if you pull the timing back, it will pry gain overall, with a good low end torque boost.  My 2 cents, I'm open to all thoughts.

I've been referencing the 360cc engines too much, the 250cc are obviously different.  I just looked up the dt1 stock, and mx specs.  Original 68 enduro supposedly has 6.8 to 1 compression.  6.4 to 1 later years.  The dt1mx is up to 8.2 to 1!  That's alot, more than the 360 mx by a stretch.  I think that dt2mx head might be closer to working than a guy thinks, although you still have to cut it to fit the exhaust.  Also worth noting, the timing is 3.2mm stock enduro.  It gets dropped to 2.3mm on the mx versions..  would be interesting to know the exhaust port timing on the gyt cylinder, vs. the stock enduro 250 cylinder.  I have a feeling it will be similiar, just like the rt1mx cylinder vs stock enduro.

This will confuse 2 and 4 stroke some more, but here goes!  The "dynamic compression, " or when the intake valve closes on a 4 stroke engine, is eerily similar to the static compression of a 2 stroke!

If you know anything about four strokes, you'll know that intake valve closes significantly AFTER bottom dead center on most engines.  About 70 degrees after BDC or so.  So why don't they measure 4 stroke compression ratio from the point when the intake valve closes?  That leaves only about 110 degrees of crank rotation for compression, not 180. 

A two stroke exhaust port closes about 85 degrees after bottom dead center.  So that 15 degrees "closing" difference justifies a whole different system of compression calculation to confuse things?  I don't agree at all.

One reason you need to modify for higher compression on a four stroke is exactly the same as why you do it on a two stroke...  more radical cam timing reduces the effective compression stroke just as raising the two stroke exhaust port does.   

Two stroke combustion is inherently different than four stroke but more importantly, a decent pipe on a two stroke provides a "supercharging" effect which means you need to have less static compression. 

I have not run the numbers in years but from memory a standard DT1 actually has a compression ratio of around 10:1 and the DT1-MX is probably about 12.5:1 if measured from BDC in the conventional way from BDC.  Euro bikes like Husqvarna reported compression ratios from BDC so they had specs of between 12 and 13:1 from what I remember. 

If you want a boost in low rpm torque on a stock engine at the expense of peak horsepower and engine life, raising compression might be a good plan.  But it usually isn't especially since these engines are already "high compression" from the factory.  And it especially isn't a good idea if installing a better pipe.  Been there, done that.