I wanted to retain the stock front crossmember along with the original vin tag on the front center of the cross member, so the engine mounts had to be planned to handle the pulleys etc on the BB Ford. In the end, I went with a single alum pulley system for the 429/460 which allowed the engine to be moved slightly farther forward. In the end, the firewall had to be cut and set back 9 1/2 inches to handle the big Ford motor.