By "GRUNT" I assume you mean low-midrange torque. Upper rpm band HP boost is fairly easy and inexpensive with a centrifugal S/C. Some folks have added turbos. Increases in low-midrange torque requires a quantum leap in both money and effort. Some choices include:

1) An aftermarket ECU change could help the ignition advance/fuel curve - ~ $1500+
2) A stroker kit in combination with increased bore can boost displacement to 3.3L+ - ~ $3000+
3) A twin screw Eaton S/C kit is available - ~ $4500+
4) Engine swap - a few 4.3L V6 swaps have been done

Choose your poison.... it's probably cheaper to trade it for another rig. If you're fond of the Gen1 body, one possibility is to put the body on a Jeep chassis. I haven't done much more in that area than consider the idea and compare wheelbases - don't know if it's been done yet or if it's realistic.

Good luck,
Frank