Yes it will fit, they came with V8's. I would not dwell on the front motor mounts. Universal side mount cross members are available. Buy a motor with a bell housing, clutch (or auto), trans from a running vehicle and get all the linkages and all drivetrain parts. I usually buy a donor vehicle and sell the body and frame after using lots of stuff including drive shaft and differential sometimes. I've put SBC and BBC in TF. With HEI. Manual and auto. You Need to mock up the whole drive train. No firewall mod necessary. There are headers that fit also, as well as Ram Horns. It's a fun project if the body is off.
What do you mean "later model HEI"? Do you just mean HEI? Not ECM/PCM, right? GM HEI's fit most Chevy V8's. You only need 1/2 inch clearance to firewall and be sure Dizzy cap lifts off.
