In the late 90's we had a '70 1/2 ton also. You won't find more room under a hood. I dropped headers in from the top like it was on the engine stand. I put a 340 in mine with a purple shaft. We took it on a 2k+ vacation and averaged 17 mpg at 65 mph (pretty much the speed limit back then on the interstates). I had a TQ/cast intake on top.
