You definitely want to transfer those recordings from the cassettes, even if just for yourself. The cassettes will degrade over time. Usually you need cables and software to transfer from old tapes (VHS, Super8, etc). But for cassettes, they make cheap recorders that transfer directly to a USB flash drive (sample link below), so you don't even need to use a computer to do the transfer. I'd go that route. And please, once you've done that, be sure to share them here. It sounds like you have a small gold mine of audio there.
Good luck!
-L2WH
The hyperlink is visible to registered members only!