Glad you've solved it. For the record, I have a lot less trouble with these old-style V-belts than I had with the serpentine belt on later ('91-on) 164s. With the V-belts there is no tensioner to go bad. Prying the compressor to tension the belt is fairly easy, and to tension the alternator belt, there are just the 13mm bolts to loosen, and a crowbar applied to the top bracket to lift the alternator.
Deep V-belts don't seem to require as much tension as flat serpentine belts, and the belts are cheaper to replace/easier to get, too.
The rubber bushings, I've swapped those from spare compressors before and you are right, a problem there leads to the belt being misaligned or the compressor wobbling (I had no chirp but a knocking noise with the a/c on). The reason the rubber bushings fail is a combination of people not bothering to loosen the bolt when prying the compressor, and of course a buildup of engine oil from spillage and leaks.
Note also that serpentine-belt compressors have four of these bushings rather than two.
Bosch is my favourite choice for belts - they seem to stretch less than Gates, so no retensioning necessary. Apologies for not recommending the US-made product - usually they are the safest choice, but for some reason I've had ongoing bad experiences with Gates belts on other cars.
-Alex