Alloy Wheel help needed!

Hi all, I recently bought a 1988 K10 gsx sgl 1.0, and realised the current alloy wheels were the wrong size as they rub quite a lot on the arches, especially under full turning. I need some help finding some 12 or 13 inch alloys to fit as I can't seem to find any to fit my car?! Also, the car is on 35mm lowering springs :) many thanks,