I agree with w8we, pick any of the ball bearing engines you listed, all will be very close in performance. The plain bushing engine (LA) has milder porting, smaller carb, air bleed low end, and is designed to be more user friendly, but has less performance. My preference would be for the TT which has great performance, quality, and price. Second choice would be for one of the OS, but costs more. Pick whatever tickles your fancy, they will all perform well.

Pilgrim