I have a friend who routinely upgrades old VWs with diesel motors and running gear from newer VWs.
He gets around in a mid '70s Bay-Window Westfalia camper with a turbo-diesel motor with a hidden radiator. It makes reliable power with good fuel economy and can handle inclines with ease.
I believe it was done in such a way that all of the modifications can be easily undone to allow the van to be restored to original condition.
