Do you want to restore them or build them into something more modern?
If the parts are all there and the driver motors aren't destroyed, you can have the drivers reconed. You can fix any issue with the crossover using newer replacement parts.
If you want to start down the road of building custom speakers, there are a bunch of different speaker builder sites where you can get info on driver upgrades. You can use the boxes to house a complement of new drivers and upgarded crossover.
If you just want to spend as little money as possible, you can find replacement drivers from a catalog company like mcm electronics.