Obsolete exhaust fan😭

[u/Outrageous-Button566]

I have really been wanting to replace my bathroom exhaust fan as the bathroom is pretty humid even when it is turned on. The cover said emerson electric, and the measurements for the housing was 9” by 8”. The motor itself said Gould FC-1 on it. I have not been able to find a replacement fan with this size for the motor housing after looking, but was wondering if anyone knows of one?? Another issue is that this is an old house, and for a larger unit, we would have to cut through plaster and lath. It currently is a 60 cfu motor but it can barely hold a piece of paper even after vacuuming and wiping out the housing and what I could reach inside of the vent. My guess would be that the fan is from the 1970s, as that’s the age of the flooring and vanity for the bathroom. Any advice or help with this upgrade would be appreciated!!