According to the '75 reference guide the part number for the early model nine woofer is 23897. I'd wager your early Santana II woofers are the same or very close.

Use a blow dryer on low/med and warm up the mounting rim of the basket. Take your time, slow and steady wins the race, the idea is to get it warm thru without overheating anything. The heat will help loosen any migrated adhesive from the rear gaskets, or cabinet finish or resin that may contribute to sticking.

IMO, the midranges in those SH II's are well worth your entry fee. I would most definitely sacrifice a pair of Santana's to preserve a pair of those in a heartbeat.