Questions about 4x4 conversion

[RHGuyettejr]

First of all let me say I searched the site and only came up with a few threads on converting trailing arm trucks. Here is what I am working with:

1 1971 chevy k20
1 1969 GMC C20 with rear leaf springs

I want a 4x4 69 GMC because the chevies body is toast. Now I can swap the body to the frame I know, but the frame on the 2wd is better as far as being pitted, therefore less prep work for paint etc. That being said, can I swap rear leaf springs and bolt up the front leaf springs and mounts/shackles from the K20 to the GMC's front end? Are the mounting holes pre drilled from the factory and will this even work? I know putting the body on the entire 4x4 frame is easier, but I want the best truck I can make, and that means starting with the better frame. To me the frames look the same as far as bend and width between cross-members etc.

Thanks for any help?