If you go through all the work to swap it out, let me know what you want for the auto.
I wouldn't use anything else.
$300 gets the torque converter upped to 3000 RPM stall.
(Dunrite out of California).
And $500 adds sequential, 100% manual control on the steering wheel.
$5 worth of shims under the accumulator pistons, gets whip-lash, tire squawking shifts.
And a $50 oil cooler keeps it all together........
Then you can use your manual, and heavy flywheel to rip your rear crossmember to bits, or shread the diff.
(auto are much easier on the rest of the drive train)
Some of the fastest Supras I have ever seen run automatics.