have everything upgraded by a good trans shop. I'd start by finding a an A500 and use the drums from it, as they hold more clutches. The power you are talking about, you'll want to get all the bushings modified to use rollers. Upgrade the servo pistons, swap in a higher ratio apply lever, and put in a better overrunning roller clutch and race. That is a good start, there might be more you want to do, but a good shop can advise you much more specifically when they do the whole trans, not just a list of mods.