I have run both BBS CH and Edition 35 (Reps) wheels, both were 8" wide, the BBS were 50ET and the Ed35 were 45ET.
Both were able to be fitted under the arches without projecting (until that is I fitted Porsche calipers, and then I needed 5mm spacers) to clear the brakes and the BBS stuck out at the front). There is minimal clearance with the calipers and the Ed35 wheels, If I fit 3mm spacers then there is a little projection, but with standard brakes there should be no problems.
A few photos are attached:
