Well that info about DRW just sealed the deal. I'll be going with the marsh 15x10's for the rear and 15x8's for the middle and oh wait only 4 wheels on a car
IF the price is right go with the auto, and since you already have the converter why not?
On the other hand do you have the ECU, make sure it will work with an auto. If not I have one from a 94 Z28 w/4l60e for sale for $75.
Use your datsun master cylinder pushrod (the one that connects to the pedal) that way you wont have to adjust anything. I did a write up on how to swap it over to the new "master".
Agreed look for a 88-92 camaro/firebird.
As far as the slave for the T56 I'm not sure I too got one from autozone but for a 92 T5. You will need the bigger master though
I'm making my own mount. Just get some 3/8" steel and use a torch and a vice to bend it to the right specs. I'm not doing those fancy Exhaust piping "humps" since I will be doing side exhaust.
I got mine on CL for $300 with the flywheel, clutch, starter, and slave cylinder (swapped that out with a 92 camaro one that is metal instead of the plastic one.)