TH350, unless you want an overdrive, then, I would go with the 700R4.
yes
Yes it will, it is the same bolt pattern.
Dextron.
It depends on the transmission and any modifications to the engine.
Yes it will, It should already have a small block Chevy in it , if it's a V8.
The 400 Chevy small block motor should have approximately 390 horse power. It should have 427 foot pounds of torque.
You will need to remove the transmission.
A Nissan 300ZX? No
It would never hold together.....
If it's a 350 from a Chevy, yes.
usually around 1200-1300 rpm
Yes you can, but a 350 is a small block, not a big block.