Well I would even settle for just over 300 horsepower, I don't want to make a pure drag bike being that I love to ride and usually put a good amount of miles on my bikes throughout the riding season. Frank, what would you recomend for 300 horsepower. You tuned my bike and I won't take it to anyone else being that your only 3 hours away and one of the best around..
At 300 rwhp, you can "get away" with the stock rods. In fact, there are several things you can "get away" with until they break. Sometimes people cheap out on builds and pay for it later.
On any turbo motor, I recommend good rods, turbo pistons, valve springs, studs, and adjustable cam sprockets. If you plan on going into the bottom end, I recommend a trans undercut, heavy duty output shaft, oil pump gear, good clutch springs and/or some type of lockup. Depending on the engine's mileage, replacing the bearings should be considered, as well as the cam chain - if you are over 15,000. Yes, I have seen motors with 30,000+ on the stock cam chain, but I have also seen cam chains break - not a pretty sight, since it destroys everything. A good builder with measure and check all clearances, and balance things like pistons and rods. Looking for someone with experience and clean shop won't hurt either . . .