Here's a sneaky trick to make that 283 a sleeper. 58CC 305 cylinder heads have the same combustion chamber volume as the old 283 "Power Pack" heads, and they've got the bolt holes on the ends of the heads for accessory mounting. They're also 40 years newer and you're much more likely to find a set of heads in good condition without a massive rebuild. The 305 heads will take bigger valves than the 283's and a little pocket porting will really make them breathe. Couple that with enough valve spring to turn about 7500 RPM, and you'll have a real screamer!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!