[Stocker]

My K20 has 255/85-16s on Ford 16x7s and 2.5" front springs with AALs & Hellwig overloads on the stock rear springs. It's an old-school look that seems just right for a working K20. That size should be fine for your 4" lift, just be a bit larger fender-to-tire gap. I think you'd need to go to a specialty manufacturer to get a taller tire that's still skinny, and possibly switch to bias-ply tires. Incidentally, 255/85s are virtually the same height (maybe even a smidge taller) as your 33/12.50s.

Edit: A few pics I posted when the tires were new: http://67-72chevytrucks.com/vboard/s...wheels&page=45