iI still have my old Denon cassette deck packed away somewhere. It wouldn't be a bad idea if I were to dig out my old tapes too. I have the full 1978 Monterey Jazz Festival on tape that I recorded off an FM simulcast when I lived SoCal that I haven't listened to in years. I really should get it to digital before the tapes become unplayable. Which reminds me I really need to get back to transferring my dad's old 8mm films to digital.
Make sure you copy them onto tape as well; always remember the archivist's mantra - "If it's not eye-readable, it's not preserved". The one thing you can rely on in re digital is, digital files will corrupt. Plus, digital platforms change faster than Joe Pass's picking, so if you want to keep your stuff, you'll need to migrate it frequently - with the associated risks.
Peter
Considering the original source and age of the tapes some loss from the analog to digital conversion probably won't be noticeable. It is something to think about if I ever get around to transferring my direct to disc and half speed master vinyl to digital.
You've not seen my antique personal computer museum. I started it for the very reason that so many things digital are tied to specific eras of computers. 
About of third of my career was designing and writing error recovery code for magnetic and optical storage devices on mainframe operating systems. A lot of folks don't know that much like magnetic storage optical degrades over time too but it would still last longer than the wood pulp based paper used today.
Trying to preserve newspapers from before & after the War Of The Rebellion is enough to convince anyone that cotton-based paper is
far superior to wood-pulp paper - at least the quality used in newsprint; standard treatment for preserving post-1861 newspapers is to photocopy it onto acid-free paper & recycle the original. High-quality modern paper will last about 150 years; acid-free will go a fair bit longer, and 150 years is the standard. No digital file will last that long - though you
do have a major advantage over most on that score, with your background and equipment. But my archival training & experience make it reflexive to respond thusly to any suggestion that digitizing something is "preservation".
And yes, I do know that magnetic media degrade as well (if not as quickly); thus my suggestion to copy it to new tape rather than just keep the original.
Peter (who will freely acknowledge that digitization
is wonderful for accessibility; thus the move in recent years for archives to digitize
and preserve)
