i think the 1990/91 250 basket is the same but the center and ring gear is different. i bought a mitaka basket for mine cost about ?100 and i gave it hell for about 4 hours and then the conrod bent. i got it off ebay from motor sport services.
not been in the work shop to day to check the sub frames (got the lurgy) will be in there before the weekend is out
by the way where in the country are you