I have a 350 in my 31 framed chevy. I also had a section that was pitted pretty bad. I cut that out, it was on the top rail and made a piece to fit in and it was bent to conform to the side rail of the frame so welded in was strong. I did not box it. The freame is very strong. If they couldn't break them back in the 39's with the roads then I don't think I could today.