[Alex V.]

3,000 lbs. isn't a whole lot. The stock Quadrajet can be a real good option, just not beset with the factory smog equipment and tune-up specs. 3.73's will be good gears for pulling, the 700r4 probably needs to stay out of OD a lot of the time - it will not hurt the engine to turn a few R's. Get it in perfect tune before throwing money at go-fast parts to try to warm it up. And that means more than just replacing all the tune-up parts - get timing at the optimum point, if the plugs aren't clean and consistent figure out why, if it stumbles or bogs, or seems to have weak points in the RPM range, figure out why, etc.

My limited experience towing travel trailers is that they catch a good amount of air behind an open bed pickup. Might be money just as well spent to get a camper shell, etc. to optimize aerodynamics than try to overcome all the extra drag with more power.

I assume it's a half ton truck?