It is very big process. You need a milling cutter to do those adapters.
Disc are from bmw 535i (e34 1989) And you can drill new holes in the disc to suit sd1 hup, and also you need lathe to do those "collar" spacer in hup.
Not sou simple..
I have got pair those adapters in my garage, but they are welded, not machined. I think they stand in place in driving.