I've seen it asked a couple of times on here abut how to make the later model wheels fit on the gen 1 hubs. Most of the time people use washers around the wheels studs to make the space needed. This is what I have done and I think it is a bit safer than going the washer route. It is also a cheap and easy solution.
I bought wheel spacers that fit the 6 lug truck pattern, 6x5.5 inch. I marked the hole that needed to be drilled so they will fit our 4x140mm bolt pattern. Drill the hole in the spacers and you are done. The wheel spacers I use are 1/4" thick. I use one spacer in the front hub to clear the brakes. I use 2 spacers on the rear drum to clear the bump stops. But then there isn't enough wheel stud to safely thread the lug nuts on to hold the wheels. The Subaru Baja wheels studs are almost the same fit where they seat into the hubs and drums but they are quite a bit longer than the original studs that are on our gen 1's. I used a ball joint press to get the new studs in my hubs and drums. Now the later model mag style wheels fit no problem.
Here is a video I posted if you are interested.