Dennis:
You might ask Bob Crites (the Klipsch crossover guy) if he will do a "one-off" for your speakers.
They would most likely be outboard, as I doubt that he would be able to re-stuff yours - which may be potted even, but he certainly has a good rep.
Once again you would need to verify the drivers in your speakers (for the chosen crossover to function as designed) as well as choosing the right crossover *design.
*I looked at various "online" crossover schematics for your application and some of the supposedly same didn't jive with one another.
It's still not clear (to me) as to if you want the stock 1500A Altec's rebuilt or if you want custom units such as those designed by ML's, but this does not affect my take/rant on it.
Good luck with the project (sounds like it will be a great setup when completed).
Here's a link to Crites...
https://critesspeakers.com
DeKay
