I would take the easier way with the HP2 Brakes, for 200GBP is very cheap.
My HP2 had cost years ago approx. 400€ with out disks and pads.

Gude Mario Audi 100 CD Autom. Bj.83 Audi 200 20v Bj.89 Audi 5000 Bj.85 Audi V8 3,6 Autom. Bj.88