Ok, I should have checked what the hole spacing is on the volvo calipers but in 2 years Ive never had them off, mainly becuase the bolts seem to be sized and I didnt want to snap them.

Anyway here's some calipers I have with their dimmesions, its a bit like bingo......

Volkswagen/Seat not sure what this is off but im lead to believe it fits a Bora
Hole spacing - 95mm




Toyota MR2 MK2 twin pot front caliper (275mm discs)
Hole spacing - 150mm




Toyota Celica GT 1994-1999 (ST202) 275mm discs
Hole spacing - 130mm




Nissan 300z 4pot Alloy caliper, sorry no pic. hole spacing is 100mm

Hope this info could be useful in trying to find a suitable caliper for the 300 series, maybe even with the addition of an adapter bracket.

cheers for the info ill measure mine when i get home today be nice if a 4 pot fixed caliper bolted up but thats highly unlikely