I'm in Axracer's camp on this. Frame swaps are oft attempted and seldom finished or look like crap if they do get on the road. Older cab on a newer chassis almost always ends up with a front track width that is too wide for the body.
Here's a really nice F3 that some honyocker tried to mate to a 70s Chevy pickup frame and this is as far as it got. I've been trying to buy it for a couple years but it doesn't belong to the land owner but some dorky nephew or something.