Acoustat 2+2 's

Hello, I have the opportunity to pick up a pair of 2+2's that are in working condition. To my knowledge the only changes from original are replacement of high voltage diodes many years ago and replacement of the "socks". It is the original owner that is selling and I think the price is very good.
My biggest concerns are two-fold:
1) keeping them running, and
2) upgrades
I am able to do my own electronic work, having built tube amps in the past, but just wandered about availability of parts and overall knowledge. There is a wealth of knowledge here, but many posts are several years old. Are there still people out there are repair these, or have the knowledge to help me do it myself?
I had a pair of the old monitor 3's about 15 years ago, and loved them - would like to get back to full range ES, just wanted to hear from other forum members on what I am up against.