That's is quite sensible.  With the seat latch removed it fits right up. 

The MX360 porting is actually pretty awful.  The MX exhaust port is 6mm higher than the DT.  This results in a power band possibly even more extreme than what your local tuner's would provide.  I tried one of those cylinders just to see what it would do and the results were not surprising.  Significantly less bottom end and midrange, takes much longer to build power and when it comes on the pipe around 6000 RPM it comes alive and pulls to almost 9000 RPM.  If you geared down to take advantage of the higher RPM power it would be pretty fast.  With the same gearing as I was running on the DT it was very lazy around town and you really had to wind it up to get it moving. 

All things considered I think the DT cylinder is a great starting point.  You can raise the exhaust port if you desire but you can't really lower it back down.  I stuffed the cases with epoxy to bring the primary compression up, widened the exhaust port significantly, widened, enlarged and reshaped the intake port, matched all of the transfer ports to the same height, re-aimed the main transfer ports further forward, hooked the rear transfer ports toward the center of the cylinder, ported the piston to feed the boost port all the way down to BDC and opened up the cylinder where the reed block lives until it would accept a modern KX250 reed block.  I did not raise the exhaust port though, there is no substitute for conservative exhaust timing and lots of trapped volume.  Love that torque.  With the stock exhaust port timing, the MX pipe comes on around 5000 RPM and makes power a little past 7000 RPM.  Very sensible for this old air cooled motor.  Much more so than the 9000 RPM power band.

The KX250 reed block is from an approximately 2002-2004 model engine.  The bolt pattern does not match but there is plenty of room to seal against the cylinder.  All you have to do is drill the proper holes in the reed block for it to bolt up to the DT cylinder.  The real challenge is in removing enough material from the cylinder to make it fit.  The block is much wider than the original reed block and you have to grind a pile of metal out.  Have to be careful not to go too far and break through the other side.