If you mean a complete A60 rear axle then yes it can be used if you weld on mounts to suit your car.
If you wanna install a LSD then remember it has to be for Zenki-type, and as you said, shorten halfshafts.
But if you mean use drum brake halfshafts into AE86 Zenki diff I really dont know and would like to know as well as I am facing similar logistical issues in getting cheap replacement halfshafts!