Frame /cab question from a new guy

[MMC SWB]

Hi guys im new here,i've been restoring cars for years but always liked the 67-72 trucks so im headed that way. Are the 72 Blazer/Jimmy frames the same as the shortbox truck frames? I have a nice 72 Jimmy 4x4 frame and would like to build a shortbox on it.Also you mention the 1/2 ton 3/4 ton cab mounts are different,can you use a 3/4 ton cab to build a 1/2 ton truck and if so do you just need the thinner rubber mount bushings or ??? Remember this will be a 1/2 ton 4x4 shorty Any help would be appreciated,i know nothing about these trucks. Thanks in advance