IDK how I missed this thread on a 8. Did you do any more planning or building? If not I'd use a Cummins 4BT for your Diesel power. I know a guy with a CJ-8, 4BT, NV4500 5 spd, Dana 300, 4" lift, 33's, full hardtop, fiberglass body, he pulls 30-34 mpg. He is big on the 4btswaps.com forum. Check it out.