G60 brakes should bolt straight onto 16v hubs and will be fine behind 15" wheels,I'm sure someone will confirm this soon,you can get a complete g60 setup on eBay,I thought all the valvers came with 256mm discs on the front,that's what mine has and it's an 89/90.also if you want even more stopping power there are several companys out there that do disc and caliper conversions for reasonable prices altho 280 is the limit for 15" wheels.