Oh the memory of my MK1 Cab,!!! Sorry going down memory lane there for a while.
Brakes yes Audi Coupe from 85-89 have 10mm bolts that fit the MK1 hence the perfect increase size of caliper.
I would look for an 89 model just because it's better system than the old 80's. Make sure when you source the part he or she confirms the caliper carrier is a 10mm bolt other wise it won't fit. The brake disc's, just ask for a Audi coupe 89 can't remember width or dimensions? Brake hoses change them while your doing the brakes, saves time and money use standard MK1 hoses the one with two huge rubber donuts around then they will fit the Audi calipers. Remember to get new slider bolts and bias valves the chances are that the old ones have rust on then. Clean the caliper with white spirit and wire brush if rust is on them. Get new Caliper bolts as well nearly forgot this is safety factor. Don't waste money on caliper paint either got down BQ get some nice silver radiator spray paint much cheaper and better finish.!
Good luck any questions just ask mate!!!
Clipperjay