With that rig and the gear/tire combo you can forget about anything below 2500 rpm. You're going to need mid range torque. Get as much as possible between 3000 and 4500. You will not be going down the road at 2500 rpm. When you pile 4500 lbs of car on top of a 10,000 lb roll back you're chugging 14,500 lbs down the road.

Lets do an acceleration run with your 14,500 lb rig.
32" tires, 4.56 gears, and in NP 435 (ratios of 4.78, 2.39, 1.37, 1.0)
Select first gear from a stop.
Run it up to 5500 rpm and you hit 24 mph.
Shifting to second drops you to 2800 rpm.
Pulling second to 4500 rpm gets you to 39 mph.
Shifting to third lugs you back down to 2500 rpm.
Running it up 4000 rpm gets you 61 mph. (You'll clear the 1/4 mile mark somewhere in here)
Shifting into fourth drops rpm to 2900 and puts you into a somewhat comfortable rpm for a torque monster.

You now have 14,500 lbs rolling at a somewhat freeway compatible speed. If you want to roll up to 70 mph for the open road you'll be looking at 3300 rpm cruise.
Crap! Here comes a long hill. You can't pull that climb at 2900 rpm weighing more than 7 tons. You're shifting back to third and running 4000 rpm to hold 61 mph.

Notice that you spend almost every waking moment in that truck spinning more than 3000 rpm. Building the bottom half of the rpm isn't going to get the job done. You need power from 3000 to 4500 rpm.

A stroker kit will add 50-60 lb/ft over a similar mild 440 build. You're going to be looking at 6-9 mpg so the extra fuel consumption of a 500" engine isn't going to be that much of a difference.

You need to look hard at compression. You want all you can get but without quench it will be detonation city. A mild cam will make a ton of cylinder pressure and hurt you with the iron heads. A set of aluminum heads would do you big favors but not everyone can spring for a pair.

My cam selection for the 440 I'm building won't suit your needs because I'm building bottom end torque.

I suggest you evaluate the speeds and loads you intend to pull then call Comp Cams or another cam company and lay it all out for them. The service is free and you can usually get a custom cam for the same price as an off the shelf piece.