Those are a nice set of speakers you have there. I think it all comes down to money or effort. speakers equal to what you have will be pricey but finding woofers from Missions good years will be hard. You might have better luck finding 78?'s on the used market.
in any case test all the speakers to see how many you need to replace. Maybe you will only need to replace 2 and you could find some 782 or 783 towers.
in any case test all the speakers to see how many you need to replace. Maybe you will only need to replace 2 and you could find some 782 or 783 towers.