To give you an another example of an 'extreme' build. This is a 1959 Morris Minor (British car) and we have moved the original firewall BACK about 4 to 6 inches. We have room for a V8 small block, but have a Chevrolet 3.8 L V6 in it now along with a 5 speed. The rear has been tubbed, but that was more for look than real function. 3x5 tube frame, you get the picture.