Digitising this much material would be a major project. The archive which I now direct in the UK was of a similar size and took 18 months for one project worker to transfer. This was done with funding from the UK lottery.

Paul Graney Archive and again

What information comes with each tape. I'm assuming that your collection has minimal information included as to what is actually on the tapes ie. Artist, and date recorded. Maybe you have track listings? I don't know what FSGW stands for but presumably it's one venue or festival or whatever. If so, were the concerts ever reviewed in a paper or magazine? That might give clues. Otherwise your only options are to quiz people's memories and organise a sampling session.

Tapes and digitising are one issue. Metadata is always a bigger one.