C 20 conversion to C 10

[boricua]

I have a 1968 C 20 flatbed with a custom built frame. Running a 454 with a Turbo400 and a gear vendor overdrive unit. 373 rear end with leaf springs and air bags. Its a really nicely built flatbed work truck. I'm planing on transplanting the cab, motor, tranny and gear vendor overdrive unit to a 1968 frame that I just got. The frame is ready to go.

I have a couple of questions about the 454 engine fitting in the 68 frame without notching the frame to make the headers fit. Is it true that if i get 73-87 454 engine mounts then the headers should clear with no problems?