what frame for 4x4 ??

[barthmonster]

I got my Son and I a '67 C10 Stepside Longbed 2wd (long-step??). He would like it to be a 4x4, the body is rust-free I can't believe it !! So which frame's should I be looking at??

Suburban '67-72 and / or '73-80 ??
Pickup '67-72 (longbed) or '73-80 ??

Any others?? Is the '73-80 a tougher deal because of cab-mounts, etc...??

Thanks guys in advance !! I'm new here and when we start, we'll do a picture-story of the restoration...