Turbo 400 question?

I got a buddy who has a 71 camaro that has came with a turbo 350 tranny. He just put in a built big block and has a turbo 400 tranny he wants to use but the current tranny crossmember is approx. 7 inches further forward than the mounting holes for the Turbo 400. Does he need to redrill new holes in the frame and move the mount back or is there an aftermarket piece he can buy that would bolt in?

the easiest way is to just drill new holes in the frame

As far as the tranny mount... will the height be the same from the turbo 350 to the turbo 400. He's looking for the easiest fix. He put subframes on the car and thought maybe he covered up the holes that would be there for a TH400 mount.