Relocating rear differential back? Suggestions/opinions

[stangs530]

Hey all! I have a 70 C30 Cab and Chassis truck with a factory wheelbase of 157in, and I want a longer wheelbase simply for my own personal cool factor...

I want a super long wheelbase so I can either have channel added to the center of the frame or simply move the differential back. Which would you suggest? On the Cab and Chassis models the frame is flat after it rises up for the rear axle and I'm wondering if I could simply move the entire rear end back? I can move it back 18in without running out of frame. I will be building my own flatbed for it so bed fitment is not an issue, not that it would fit one anyway. Are their and negative affects from moving the rear end back as far as too much weight on the center of the frame? This is my first project like this so I am just making it up as I go.

I tried searching but I keep getting an error message. It seems like not many people restore or mod the C30's, just the half tons.

Thanks guys/gals in advance!