AAAHHHHH!!! Now it all comes out. You're information sorce is a F@RD guy!
And also '50 era trucks are a whole different story. The reason your "friend" did a chassis swap is because he wanted all the things you mentioned, and probably independent front suspension instead of a straight axle. All things which your era Chevy already had.
Zenish is right, the only thing separating your chassis from a '71/'72 is the front suspension/brake components. And maybe your rear end (6 vs. 5 bolt hubs). Otherwise your frame rails are the same. All components can be swapped from another truck to your frame. I just think it's easier to find a different frame that's all set up. Then you can do a nice job on the chassis while it's all apart, and you don't have to mess around with moving the body.
Just depends on how indepth you want to get.
