Ramcharger cam questions

I went through the same thoughts on my F-150 4x4. Honesty the best thing you can do for a heavy vehicle is displacement to get the torque up, a 390 or 408 stroker would be nice. What is your emission laws like? do they Vin the displacement or go by GVW?
Oregon is 76 and up, I pass with a 460 moderately built with cats and some tuning.