The cab I scrapped off a '73 K10 that was stripped of all the interior parts and badly rotted weighed in at 450 lbs at the scrapyard...hope you have strong friends!...I'd say at least 4 guys are needed...I've lifted them off alone using a gantry crane or a nice thick tree branch with a chain falls or a bucket loader before....I dont like using humans to remove or install beds or cabs,too often one of them has a back go out at a bad moment or trips,etc,leading to disaster...
I tried using a engine hoist once to install a cab we had sitting on the ground ,but it wouldn't raise up high enough though..I installed that one by jacking it up a little at a time and piling cribbing blocks under each side,once I got it high enough I used 2 sawhorses 8 feet apart with some 3" channel iron across them to support it high enough to roll the chassis back under it...4x4 wood posts would work OK too..