mine is 4" aluminum.

I used Strange for a chromemoly driveshaft, however I later realized I was exceeding its critical speed on the top end. I am going to have to go with a carbon fiber unit to have a margin of safety. I'm running 3.91's with 28" tall Nittos.

In another post you mentioned US Cartool makes a kit to swap the transmission in, do you have a link?

I might not need the 3,300 torque converter yet. I still have a stock 360 in the car and my planned engine swap is a year away. But I will be putting 500+ hp when the time comes.

I'll definitely need an upgraded driveshaft.

Any other parts I need to consider?

I highly recommend installing the entire chassis stiffening kit from US Cartool. It's also a good idea to weld up your K-member and weld up the torsion bar crossmember solidly a crossed the floor. I would also reweld your shock towers to the inner fenderwells to strengthen them too. Give John at US Cartool a call and let them know what you are doing.