I don't think so. From what that I've heard the early 1500's had a different size rear brake rotor than the later, although I do think that there is a way to adapt the rear wheel to work. Do you already have the newer wheel? I'd compare the two to find the difference. Otherwise if the wheel is from a trike conversion, I'd see if I could get the caliper and bracket with it.
Ok here's the skinny. I looked up part numbers for the caliper bracket, caliper, pads, rotor and rear wheel on babbits.com for a 1988 and a 1993 GL 1500A and none of the part numbers match. I remember a GWRRA member had a rear wheel bearing go out at the OH district rally a few years back, somehow he came across a used wheel/tire but there was a problem with the rear brake set-up. Someone ran up to a independent Goldwing shop to get the parts needed to install this used wheel. Which parts needed to install this wheel, I can not tell you.