IMO, adjustable plates make sense for any car, so you can dial in matching caster and camber from side to side. It makes a big difference in tracking and steering feel.
Fixed plates give extra negative camber but not adjustable, obviously. Alignment will still likely be off side to side due to a 45 year old body shell and less than perfect quality control when the cars were built.
Some corrections here...
Not sure how camber plates would wear out the inside tires. Simple...by leaning the tires onto the inner edges. If you're tracking the car you can run negative camber of 2-3 degrees and still get even tire wear, but if you have negative camber and drive moderately you will wear the inner edges. (Incorrect toe settings can wear the inner edges as well)
When you lower a car, it automatically gives you negative camber, and you would get inside tire wear. Not really. You get a little extra negative camber when you lower but not a lot
Camber plates are to correct for that by giving you more pos. camber. No. Camber plates give more negative camber to help keep tire edges away from fender lips as you go lower.