that clip on fuel rail is for attaching a fuel pressure gauge, so you can test pump and fpr function.
so you redrilled the MK1 hubs to 5x100? if so you might be able to use early Passat VR6 discs, they are 5 stud but use the same hub offset as G60 4 stud discs. VW only though:
357 615 301 A - 280 brake disc, 5x100 - 38.83+VAT
also you can get adaptor brackets that allow you to fit G60 calipers & carriers to a MK1, or as you say you could go the vaux route. If you have a random 4 stud 280mm disc sat about test fit it to your setup, if it fits fine the passat disc above will bolt right on
