12” bass speakers

Greetings, I may be getting a chance to restore a 1968 Coral 6-12 cabinet. It has no speakers in it at all but the cab is in great shape. I’m on a budget but I’d like to be able to either play a 5-string (w/low B) or convert one of my 4-strings to do drop B or drop A tuning thru it. I was...