I agree these trucks need a certain diameter of tire just to fill out the wheelwells to give it the right look. Too small of a tire just looks wrong IMO.
Find some stock Van Rallys for the front they came in 6 & 7 inch widths and I do believe had a few different offsets. Pbbly find them with tires already on them cheap....give you a chance to check your clearances before buying new rubber.
Your local tire shop could probably source new rallys in a whole bunch of different sizes & offsets also. I bought new steel rims for a Jeep it was around $80 each any size/offset I wanted.