the ford axles have the pumpkin offset 2 7/8" (the LH axle is longer than the RH), that's why people advocate shortening the LH side and getting another RH side. you don't NEED to do that, they fit as is.
'66-'67 B body are 59.5" wide (similar to the explorer) 68-70 are 60.125" wide (similar to the XJ cherokee).
the ford rears and the B body rears will both require spring perches to be cut and moved, as well as the driveshaft shortened. if you want to use standard offset wheels and get some decent meat in the rear, the Ranger (or explorer rear with the 1 side shortened) are probably your best bet