[team39763]

Those mounts will work fine if you're planning to run the 700r4 or 4l60e trans. I ran the th350 with those style of mounts and it moved the motor too far from the trans. I ended up bying the S&P 1" setback adapters for mine. The S&P's made the motor sit up higher and gave me a little more exhaust clearance around the frame and control arm.
Start reading up on how you want to do you accessories if you don't already have them, I think which type you use affects if you can fit A/C equipment easily or not. Alternator wiring needs attention - you may have to run a resistor in the wire going to the plug. If you're gonna use a Th350/400, you may have to change the flexplate and/or get a pilot spacer/adapter(if you don't buy a custom LS1/Th350 torque converter).
You going carbureted or sticking with EFI?