Porsche 928 Slots on Coilovers

Hi All

Need some advice on fitting porker wheels on my Mk1 cabbie. Iam trying to figure out how big a set of spacers I will need and how much this will clip the arches. Stretched tyres are an option but I am unsure how much stretch I can get away with and still keep it practical/useable on a daily basis.

Thanks in Advance


Les