I Put a 383 with a 727 in a 56 Coronet 4 door. I cheated though and used a fat man fab front end. I put A/C in the car, so had to weld up the firewall. I also had to run an electric fan. I used the original radiator but put the fan as a pusher in the front. I had to massage the tunnel a bit, and I put in a B&M shifter for the trans.

I was able to use the origianal trans crossmember, I just took an old e-body cross member that was in bad shape and cut the mounting lug off of it. I then welded it to the original cross member. I have about a half inch between the Passenger side head and the firewall.