In your boots, I'd get a MC18, and put a MC21 bottom end into it. You get the availability of the MC18 in your area, and a bottom end that you can still get crankshafts for...

I had an MC18, all stripped down for racing. Went really well. Then I got an Aprilia RS. Went well, but went bang a lot.
Got tired of that, and got another NSR, an MC21 this time, which is an as yet unridden work in progress...
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The Chopster