I've gone as far as getting the cover off, having a good look around, and starting a BOM to order parts. I'm not on any sort of schedule so it just depends how much free time I have and when I actually order the parts. I'm also trying to wrap up a Marantz 1060 restoration first.
Polystyrene? Do you mean polypropylene? Polystyrene caps can get enormous in anything more than picofarad values. Look around at LeeStereo's rebuild threads. I believe his rule of thumb is film caps for anything under 4.7uf. And polypropylene are best, signal wise, but I'm finding the sizes a bit restrictive in that regard as well. I think finding the right film caps is the hardest part.
I'm hoping to get some feedback from fellow AK'ers in the thread I started on the A-7 once I get my BOM a little further along. Also, the stock film caps may in fact be great sounding already and not need replacement. My main goals are to replace all electrolytic caps, any noise prone transistors such as, but not limited to, the 2SA720 and 2SA726's, as well as any questionable components subject to abuse over the years, i.e. burned resistors, rectifier diodes in the main power section, etc.