Easier to do this....
1, Mount the Z32 caliper on the MK2 strut. It fits so perfect it's scary. Even the stock MK2 mounting bolts have the exact same thread pattern and length needed.
2. Buy discs in 11" diamter from AP Racing (280x25), Coleman (11X1) or Wilwood (11X.81). Again a perfect diameter fit for the stock Z32 caliper and pads fitted to the MK2.
3. Fabricate two hats that are flat with a large center hole for the hub center, four holes (100x4) for mounting it to the hub and finally the outer holes to mount the disc. Yes there are VW discs, but the hat is just a little too tall and you will need to machine the inside of the hub and VW disc.
4. Fabricate four shims shaped like the pads because you are using a narrower discs than the stock Z32. The thickness of the shims depends on the disc width used.
5. Use a 1" adapter and mount wheels that are the appropriate offset, because the caliper is incredibly wide. Or find wheels with a thick hub center (like these
http://ca.geocities.com/mk2supra1985/wheels ) . Notice on the Japanese web site they used adapters as well.
I posted a picture of the shims I made.
http://ca.geocities.com/mk2supra1985/brakes
My 16" to 17" wheel conversion is the reason I said it goes hand in hand with another project I did. I already have the adapters. Easy to find wheels if you use the right adapter.
I wanted to do the least amount of machining possible. The shims are easy to make, the hats are the only thing that may cost you money at a machine shop. These parts never wear, so you never have to replace them. Every other part (pads and discs) is easy to buy and replace. The less we take off (machine) the less strength we give up in the stock parts.
That's why I didn't go the route of using the stock Z32 rotors. Remember the stock hubs have no races so if they wear early you will have to resurface the new ones before installing them. An adapter is needed to hold the caliper and still an adapter for mounting the wheel. The discs need to be redrilled (with both bolt patterns on the discs there may be balancing issues).
I will post everything I do once I complete the project.
I will be trying the stock MK2 wheel and tyre setup with a 1" adapter on a MK2 to see just how it fits. If remember correctly the wheel did go around the big caliper... just.
There are so many variations on completing this project. That's why I didn't want to say anything till it was figured out.