Unless any existing tapes have been kept in correct archival storage conditions
for all these decades.
The current owners may find all they have been hoarding
are boxes containing reels of coagulated mildewed compost...😢

At the very least, they may need to be carefully baked and repaired by 'pro' restoration facilities.
With no guarantees of usable audio quality...

Otherwise the first attempt at playback might result in irepairable damage
or complete destruction.

Tape Salvage & Transfer