I helped a friend install a 454 in a '79 CJ-7. This was a sand Jeep and the motor was a 10.5 to 1 compression with a BIG Comp Cam, desk top dyno put it at 550 HP. It fit very well with fab'd fenderwell headers. We had cooling issues. He ran a 4 row Mepco radiator with a clutch fan and an Electric pusher. Cooling worked OK for general street driving, but it was hard to keep cool on the dunes (Motor working all the time). I wanted to try an aluminum cross flow, he decided to install it in his wifes '71 Monte Carlo.
I have a SB 406 with 10.5 to 1 and run a Mepco 4 core with no issues, I have 2 other friends with 406's that run on the street and Moab with no problems as well. I really like 400's and 406's. I think it really comes down to what kind of power you want to make and what you are going to do with the vehicle. Small blocks can make great power when built right- and they are cheaper to build. My .02
