Thanks for the particulars on the 318.
Interesting that you saw 229hp from 372cfm, that's really close to the 0.6hp/cfm that I use as a rule of thumb.

An actual 229hp would be a big improvement over the 120 or so hp the truck may have come with. In this day of seemingly unlimited horsepower figures, those small numbers seem like peanuts but the percentage gain is what's important to how the car feels.

I'd be leery of taking a 318 block over 500hp but then again 318s are nearly free.

Fast68, I think the biggest thing holding this combination back is the dinky ports. It takes more pressure to jam air through a small hole. Other dyno tests of turbo engines have shown that intake port flow is very important to achieving max horsepower. If the airflow was increased to increase baseline power, then it'd probably follow that hp would increase proportionally. I'm not so sure if a larger cam and more compression would translate the same, though.

R.