440 on a budget 6.4 if you have the funds. As you know it's a little more involved than just an engine swap. With modern cam grinds you can have a very street freindly BB. Top it w/ a six pack if you want max MPGs. I get 15 to and from the track. That's w/ an auto and 3.91's and why do you need to "clone" a 70 500? Does he just want the stripe? Mine is an XH car (came w/ no tail panel and unpadded door uppers and no pockets on the door panels)