Been a while since I have updated this, so lets get started..
Last time I left off I was mocking up the motor/trans combination. Again it was a '70 Chevy 292 with a 5LM60 (NV3500) I had pulled from a '92 K1500.
Mocking up the motor for the engine mounts:
You can see the cardboard template of the firewall I had:
Clearance between the harmonic balance and crossmember was a little snug, but I left it so I could get the belts on/off when I needed:
Roughening it in:
Passenger side mount:
Exit of the shifter will be perfect with the bench seat: