Personally, I'd go with 275x60x15 w/8" rims. I've got 8" rims and have several 275x tires...even 295x60 (I've cut wheel well edges) and like the look of those, actually. The 295's look cool if you like the tall tire look.
I think 255's will look very skinny. You've got 8" rims...take advantage of them.
T