Sounds like you are doing it right...I put a 440in my 56 Belveder .I had more problem with headers than anything else..but after I ran it for a year I wanted to get rid of the stock front end..A surprizingly easy swap over was the Volare type k frame..Mine was from a Chrysler 5th ave . I got a complete doner car to take it from so I now have the steering colume with tilt wheel too. But now even more header problems..and I have A/C , power windows, now power steering and disc brakes..the steering colume went in like it was made for that car..My Ply rides straight and smooth..best thing I did..I had to make my own motor mounts.. Good luck