Choosing pistons
They can be built to withstand a 1000HP. I don't want to get off topic, but here ya go:
Extreme Automatics Keep in mind you have to get the adapter plate or bellhousing, that starts to add up. But you are also building a hell of a motor, so why penny pinch now. :)
The 42rh I believe can be built to withstand alot of power, it is pretty much a 904 with OD, and we all know the 904, if built right, can withstand some pretty serious power.