I can’t speak to the AI voice generation part of this, but you might be interested in the Domesday Duplicator for digitizing your audio, especially if some or it is slightly degraded.
The project was originally designed for laserdisc, but it’s been expanded to support VHS and cassette tape. Traditionally, you would play your tape on a cassette player, then the built in analog circuitry would convert the magnetic signals into audio, amplify them, and feed them to a sound card on your PC, which then converts the analog signal to a digital audio stream.
With the Domesdsy Duplicator, you record the raw magnetic signal from the read head and directly digitize it into a bitstream that you can then process as needed. For DIY archiving from an analog source, it’s one of the best options for signal fidelity, and it will give you the truest representation of what’s actually on the tape.