I'm in the process of buying a second-hand Peavey 410 TX 4X10 Inch Bass Cab from a friend of mine, I'm buying it for use as part of a bass rig with my Fender Super Twin amp, I've done some testing and as far as I know it just needs a complete set of replacement speakers to get it working again, it could also do with a good clean-out while I'm at it, should be a good project for next year.
The bass cab is rated for a maximum of 700 Watts into 8 ohms, so if I wire-up the new speakers in a series/parallel configuration, each speaker needs to be able to handle 1/4 of 700 Watts, or at least 175 Watts by my calculations.