Great speakers.
The crossovers will need to be rebuilt at this age.
Best results intact found have been when they are biamped with 771 or 1224a units.
These units had one if the best response curves and sound great.
My dad built a pair of them from a kit altec offered in 1975. The sound stuck with me till I saw a pair on eBay in 2005. I bought the pair and rebuilt them.
I tried the inboard crossover but it had limitations and sounded garbled. I have read elsewhere of some interference between the drivers being the issue.
My move to the biamp brought clarity and volume that pasted a grin on my face.
Good luck. If you do them right you will enjoy them.