Altec Crossover Upgrades?

Hello......I have several sets of Altec 920-8A full range duplex drivers, 12 inch, 8 ohms, 150 watts. Originally from the early 80's, these were primarily used as secondary or back-up applications in theaters, lobbys, concert halls, hotels, etc... They were installed in ceilings, columns, and in walls.
I would like to use these in custom built stage monitors, about 3 cubic feet of internal volume. These will be braced and ported.
What can I do to these simple crossovers to get the best sound possible? Capacitor brands, types, and ratings? New coils? Wiring? Can I make any other changes?
Any and all advice will help. Thank you in advance!

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