I recently picked up a 1966 Chevy 6 cyl, std, long bed (ie who cares). It is definitely a rat. I got it off a guy who got it off of a farmer, etc,etc. Anyway, he had overhauled the engine (in the truck) with new pistons, rings, and a complete rework of the head and had the carburetor rebuilt by "someone who knew what they were doing". It would start and would more forward and backward a few feet (no brakes).
In other words, I hauled home a pile of scrap that should have been parted out years ago.
I like to tinker with these old trucks, but this thing may break me (my back and my wallet).
Attached are some pics: