Just another random thought. If this is the one that has been rewinding the source coil then my guess 'now' is that the voltage is getting too high for the points to take without going arc welder. Had that issue when i experimented using a lighting coil for ignition source. I wonder--seeing you've gone to a lot of trouble rewinding--if you could hook in a regulator [adjustable would be good if they exist], might have to be 12 volt AC even though its theoreticaly a 6volt AC system but voltage goes above 6 i'd think on the source. So would need to 'somehow' be connected before it gets to the points & condenser. Then again i can pick holes in that theory easily.

hang on quick question. is the condenser supposed to be grounded to the stator? as it exists currently, the condenser is just sitting freely in a little slot with no bracket holding it in place, sometimes it touches the stator and grounds out but i would imagine sometimes it doesnt contact firmly. if it is supposed to be mounted, we may have the source of our problem. thanks!

While this is not a 250 you can see in this video that the condenser is screwed down to the stator plate. 

condenser attached to stator

Yes, case should be grounded.

Ok, if not grounded, that'd account for the erratic points sparking for sure. If you needed to, you can mount the condenser anywhere convenient or up at the main coil itself like Hondas do which gets it away from vibration & a lot of heat. Just buy one of these. But if you have a bracket on yours just screw it down. 

Hi again guys, more bad news. I used a band to hold the condenser to its bracket and still no luck, somewhat weak/erratic spark. I then took it off to see if something had changed and it hadn't but I thought I'd try cleaning up the points and setting them straight. Now the bike won't even turn over. Spark seems acceptable, but not as hot as before. Getting very disheartened. Still not giving up because how can I. Contacted the guy who had a spare stator, may buy it all from him at this point. I don't have a capacitance tester so I can't check the condenser status. I still have another from my spare stator, might put that on. Any thoughts are appreciated. Thanks again.

Just polished the plug and put it in, here's the spark I'm getting. This honestly doesn't look too bad to me, but please let me know if it seems normal or like it might be the problem. I tried kicking with choke on, no luck, and then tried ether and that also didn't help. These videos are with the drill and then just giving the kickstarter a weak push with my hand, some spark in both cases. Let me know if it seems good or not. Thanks.

photos.app.goo.gl/h9cwj77eF1vrmAy57
photos.app.goo.gl/5XrTKgW6TkXHeg1j6

Maybe try a "new" plug then you'll know its clean. You said 'pollishing the plug' but when they short out from burnt on oil they short deep down at the base mostly so any cleaning on the end doesn't help. New plug wet with oil won't short & its only when the oil gets burnt on that it then shorts to earth [in my experience] Think i'd cut that doubtful condenser out & mount one external to earth anywhere on the black wire or at the plug coil. Black wire down the loom from the mag might have a short black female covered connector so could connect condenser there with a wire then earth condenser at a convenient place for experimental purposes. Or get a 'new' condenser 'that screws to the plate' as per original. Only other thing i'm wondering has the crank key fallen out or got pushed out & away as the flywheel went back on. Frustrating i know & sympathise. We've all been there. Spark i can see looks good enough to run in first video except didn't look 100% regular but if shorting to base then that'd account for that, & under compression it would all be going to earth & none jumping the gap. Once again, just my thoughts be they right or wrong. Best of luck.

Hey again RT, thank you as always for your continued support through this incredibly tedious process. Firstly regarding the condenser, that sounds to me like a good idea. Where could I get a new condenser? Do you happen to know the spec and if they're hard or easy to come by? I think I'll mount mine up under the ignition coil like you showed. Also regarding the plug shorting in the base theory, that may actually have some merit to it. I noticed through the course of testing with the drill that there were some instances where a small spark would be visible at the base of the electrode in the plug. I had chalked this up to debris shorting somewhere in the plug and so i cleared out some gunk that was around the area, but if what you say is true it could be our missing link. I'll go find a new plug or three and see how it works out! Thanks again, I'll keep you posted, let me know about the condenser.

New Condensor