Here are some disc dimensions which maybe could be used with
Fiat Coupe/Peugeot 406/ Alfra Romeo GTA calipers:

(original discs Cosworth 4x4 --> 278x24 - height 36mm)

Focus st170: 300x24 - 44,7mm
Peugeot 406 V6: 305x28 - 28mm
Peugeot 206RC, 307 2.0 16V (177hp), 307 HDI 135: 302x26 - 34mm

I think with the 4 pot brembo calipers and Peugeot discs from the 206, 307 it should be no problem to make a proper home made braking kit.