[Mrmerlin]

I think Mike is confused,

the rear wheels with a 65 ET will fit fine,
and you can probably add 17mm spacers to push the tires out to the wheel well fender lips.

NOTE the lower the ET the further outwards the edge of the tire side wall will be,
so an ET of about 45 will not require spacers, and also considering tire width,
and the wheel tire edges will be running very close to the outer fender wells in the rear.
an ET of 65 is the stock ET for the 928 both front and back.

Remember that the rear wheels deflect upwards and inwards at the tops of the tire when the wheel compresses.

to figure out the correct spacer for the rear ,
install the wheel tire package,
roll the car to settle the suspension.

Then measure the top edge of the tire at the rear outer fender well lip use the side that has the least number
then subtract 5MM from this number,
this is the spacer thickness that you can use to move the wheel out from the centerline of the car.

NOTE to increase the fender well clearance,
use both hands with thick leather gloves,
place both hands next to each other,
then gently pull the fender lip outwards,
the metal will bend out slightly