My MC21 has been sitting in my garage for about 6 months now while ive searched ebay/tradinpost etc etc for a new motor for it as the one in it is fooked, but nsr's are a rarity around here. Best price from an importer was $1800 with no guarantees
, so anyway are there any motors that will slot straight in? are most 4 stroke 4 cylinders too big? theres usually a few 600's around thatve been crashed, even a busa locally being sold 
Ive seen a website of a fellow here thats put a XR600 into a RS frame, and also the cr500 nsr. Both interesting but im kinda looking to make a managable bike in the end.
So if let me know whats do-able and whats not
Cheers
Tim