Upgrading drivers of an existing old cabinet (pics)

I didn't ask. Does the woofer work?
If it does how does it sound?
I can tell you that the crossover shown in the picture isn't for that midrange with the back-cup; that mid does indeed do 800Hz to the stated 12kHz, in fact it can do 350 to 400 Hz easily with Bi-amping and a steep XO, its in-cup Fs is around 180Hz from memory
 
If the woofer works and has no coil in line and is working without any crossover (usually going up to 4khz then) a simple piezo horn would do which goes down to 4khz.

Just use 50 to 100 ohm from plus to minus for the piezo and a capacitor of 0.2 to 0.47 mfd in line. For the phase make a listening test. The mid opening must be closed after putting the drivers out if necessary.