Best new drag radial and largest tire size for a 1968 dart in stock wheels

This is a build that has not hit the road yet. 3.91. Gears in an 8 3/4 rear. The rear has been shortened to 49 and change so my measurements are not transferable to others. So, the 255s have at least a hands width on both sides. Wheels are 15x8 I believe.