FIat Coupe brembos sit quite far in towards the strut, so you'll need to find a brake disc to suit (unless your going custom but that doesnt fit in with cheap)

406 coupe brembos are also quite far in.

Seat Ibiza Cupra ones are probably more suited, I can take any measurements you need from a set of them if you like. And the above two.

The other ones I had looked at were Clio V6 calipers, and a set of RX7 ones I had. Was a different car, but similar problems.

If you can make brackets yourself, then in theory any of them will fit. I have a big disc catalogue with sizes and offsets and the like so can do some working out for you if you tell me how much space there isn't

Are there no vauxhalls that you can rob bits off?