I don't think it's from a factory Altec cabinet. Most of the cabinets from that era like 606, 607, or 612 used a port that has less width and more height to its aspect ratio.
There were a lot of non-Altec plans for cabinets for Altec drivers, and even some aftermarket cabinets
As for value, it is the most desirable 604 in excellent condition.
But, it comes with a bonus, an original N1000 network. The crossover is probably rarer than any of the 604's, and it's value to a collector would surprise most folks.
I would just store the network and build a scratch copy, copy in the electrical sense.
It's the best tonally balanced and best overall sounding 604/crossover combination, and last of the 604's with a multicell horn. It's as good as it gets for 604's.
Properly presented at the optimum time of year, it's value should be right at the very top of it's game. I'd want a replacement value of 4K on my insurance for the raw driver and network. maybe more.