Jared,
Good point to bring up if you are considering adding AC to a non AC car. Yes, the top radiator inlet tube for a GS with AC turns at an angle to avoid the AC compresser. A non AC GS would have the inlet tube coming straight out. You are also correct, the pulleys would have to be from an AC car. I would assume that the compresser pulleys would come with an aftermarket unit, but you may need to find an AC pulley for the crankshaft.
John Egel