Here's a little more info on the Altec line. I've been tracking down the Altec line for a couple years and now I am tracking down the JBL line.
Here's an A7. It uses the 511b horn with the 800 series driver
Next up the food chain is the A5 which in this case uses the 803 horn and a 288 driver
Both are crossed over at 500Hz. There are a bunch of different variants you can do, I have a buddy that uses the 203 horn which is a 2 cell horn. You can also go with a 1003 horn with is a 10 cell. I think the 203 throws the sound forward a little too much. I like the dispersion of the 1003 or the 803 horn better.
These are very finicky and revealing. They sound great with a 300b tube amp and live recorded music. They are not going to sound great with rock and roll blasting....however, if you like jazz, vocals, piano etc....they can be magical
Not for everyone but to give you a few ideas