At speed, a 28" inch tire will usually grow to 29 inches, depending on the brand and type. I think 4.30's are probably going to be right on par with what a 408 stroker running to 6200 would work best with. If it keeps pulling to 6500 rpm or higher, as in going faster by raising the shift point then I would say 4.56. But at that point the emphasis becomes much more strip oriented and less street. If it stops pulling at 6200, 4.30 gears are all it would ever need.