There is no such thing as a replacement driver, except the original factory replacement. Because of drivers unique T/S and acoustic parameters, the replacement will not work properly in the box you have and the different acoustic parameters require a complete crossover redesign.
Even if you wanted to use different drivers, you would have to refoam yours and get them working, to measure the T/S parameters.
So your choices are refoam or scrap. It's your call.