[Coley]

As mentioned the hp number is often more for the car guys....torque is what gets these trucks moving quickly in most situations.
If you want to rebuild a motor why not go with a 383 stroker kit to get your torque...as well as pretty good hp numbers.
I think the block has to be clearanced in a few places in the bottom end but the machine shop would take care of that.
After that...the rest is parts.
As for heads and cam...I would stick with 1.94 valve intakes (good for torque) but go for 1.6" exhaust.
In terms of the cam....more lift is the way to go for torque in place of the long duration stuff. If you go for the long duration 'lumpity sound'....you can say adios to a lot of your everyday around town power near or off the line.
For the intake a dual plane (not single) is what you would want to stick with or go with.
Top it all off with a professionally built, correct Quadrajet and you are pretty much good to go....apart from a few details, lol
My two bits.

Coley