20" or 22" wheel sizing tips

[strokd 84]

Hey guys -

My 84 swb is below. I'm looking for 20's in the front and 20's or 22's in the back. I forget how much I lowered my truck (6 years ago...), but I measured the distance from the cement to the trim on the outer lip of the fender as 27.5" in the back and 27" in the front.

I don't want to run rubber band tires. Instead, I'd like to know some wheel backspacing that has worked out to tuck the wheels up inside. And I don't mind cutting some of the inner fender lip. Some of you guys are tucking 20" or way bigger wheels on trucks that are lower than mine. What kinds of wheel backspacing and tire combos have worked out?

Also, my truck has a 383 with 3.42 gears. It has 10" wide tires now and doesn't hook up the best. This thing isn't fast, but it has some torque, and I don't want a skinny little tire that just spins...

Any help would be greatly appreciated!!!