You can make 375hp with that 440 but you won't like the way it runs in your truck.

I've built a smogger 440 just like yours. I put a mild cam in it and a set of 440 source heads. It still didn't have the bottom end power I wanted and that's in a car, not a truck. To get the smogger 440's to haul you need a decent torque converter and some aggressive rear gears. I started with a 3.55 gear and a stock converter and it was not near enough. And your truck is probably 1000lbs more than my car was.

I would clean up the engine, regasket it, install a new timing chain set if it needs it and run it. Recurve the distributor and dial in the carb of your choice. It won't have 375hp but it will run, tow and 4x4 well.