I dont claim to know a lot about these old trucks but I put a 39 GMC on a 1980 c10 short frame and its a blast to drive.Had to weld two angles across the dip in the frame at the cab for mounting it and moved engine back 6 inches and rear forward about 2 inches. I got power steering power disc breaks and I think due to the engine being back more than before it drives great.It does take a while to mount everything. I did it because the truck was a basket case when I got it,dont destroy a good original truck.
Gary


Drag em home, fix em and drive em.