4x4 Frames - Converting 2wd Long box to 4wd on a 1965

[ND-1965C10]

I currently have a 65 c10 Long box and in a few years will be getting a second from my uncle. Since I already have one that I think is pretty nice I am wanting to take my uncles and use it a little more instead of only taking out on nice days for cruising. I would like to take his and make a 4x4. It is a long box. I am in the process of thinking about what I will need to make this project happen and wanting to round up the parts now so when it is in my possession I can get to work right away. I am thinking it would be easier to get a new frame to put under it. About 5 years ago my brother took a 78 and did the same thing so I feel confident I am not getting in over my head.

My thoughts are that I want to find a 63 to 66 k10 frame and might have a line on one where I just need to "run" into the guy. I was recently thinking through that I might be able to use a frame from a 73-87 body? Has anyone done this to where you can tell me if this is possible or what challenges I will hit? With my brothers there was not any issues (cab mounts were a little different only but that could have been because it was a 79 frame).

Any insight/thoughts/suggests/help would be greatly appreciated! A couple pics from my brothers to get you interested in the process!