Just put a 1973 black motor 250cc Harescrambler motor on ebay. It is on standard bore but will need mains and maybe a rod bearing and boring. Topend is free and not stuck. Pretty much complete except for ignition and ignition sidecover. Has I am sure alot of great parts like a very good clutch actuator but should be plenty rebuildable.
Larry, Where is the motor located on e-bay?
It is under Penton. If it is not showing yet look at some of my other stuff and click on sellers other auctions.
specifically, see
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=1860431551