Just use an early trans, so you don't have to deal with the lock up stuff which HP parts are limitied.

You don't need the bigger drum from the 999. You can buy thinner discs and run 5 in the 904 drum. You will also need a shim kit to get proper clearance. And mixing parts is a PITA. Don't deal with that headache.

Put good bands, clutches, and steels in. Get a Valve body from A&A, rebuild the trans, put in a blocker rod and put in a billet piston and 4.2 lever.

I have nothing else done to my trans and I'm running it with a 7100 stall. 878 hp 563 tq...

No trans brake though, so Rick may be able to recommend what else you HAVE to do.

I have less than $800 in my trans besides the trick custom valve body Rick built me. I have 37 1/8 mile passes and 52 street miles on it. No issues and the oil pan shows no problems...

Just my