I would seriously measure up a long box S-10 chassis. All the suspension stuff is readily available and the swap makes the truck drive like a brand new one.
Forget trying to weld on C-body parts etc... mount the body and cab on a frame that is ready to rock and that can be picked up at a wrecking yard for nothing. that's my
My buddies International 440-4speed on a S-10 chassis
then make your own motor mounts and drop in the Mopar engine.