Looking for a slant builder/guru

First, insure you understand what "power" means. That occurs at high rpm, with the engine screaming. So, unless you plan to drive around like that (sometimes looking childish), max HP may not be the most important spec. What most people describe as "power" is really low-end torque, think a Harley glugging along in high gear, ready to torque it out w/ a twist of the throttle. That is why most V-8's were sold w/ 2-barrel carburetors.

If you want power (high rpm) with good torque down low (and better mileage), look at Rhoads lifters. That will let you run a high-lift camshaft and still a good idle. I "think" that small-block lifters might interchange w/ slant hydraulic lifters, but check. Slant lifters are oiled a bit different so might not work even if the bore is correct. Would also need a racing hydraulic cam, which might be a custom part (anyone seen one?).

First thing is to look at your ignition. I don't know trucks, but sometime in the early 1980's Chrysler started the "lean burn" ignition which was problematic. If so, changing to an HEI module is your easiest fix. You will probably get more gain for the buck from a bigger exhaust than a bigger intake and when installing the engine is a good time for that.