I have a TRX450R that was given to me. The transmission and cases are shot, so I need a new engine. I've decided on a 250R engine. I plan on building this engine to meet the following criteria: reliable, 55-60hp, broad powerband, runs on pump gas. I can just about bet that I'm looking at 330+cc with porting, matched pipe, etc. My biggest questions are which specific parts? Which brands? Does the tranny hold up at that power level? Clutch? What size carb?