The best way is to get a Sony Betacam SP player or recorder and use the Component Betacam outputs. NOT the composite output. Probably any I/O box that has Betacam component inputs will do a good job. Like Black Magic, Aja and Matrox. You will need three identical length BNC video cables to hook them up. Plug them all into the correct connectors. Such as Y to Y, B-Y to B-Y and R-Y to R-Y. Babysit putting in the tapes one at a time and sit back while the computer records the tapes in real time. You don’t need any tape control. Meaning you can just manually start the tape playing and the software app to record on the computer. If you think you will need to reference the tapes again in the future to recapture some footage (I don’t know why since you can easily make copies of the digital files as backups), then set it up to use the timecode off the tapes to be used in capturing and to label and keep track of reel/tape numbers. I don’t know about Thunderbolt for the I/O. Maybe someone else can help with that. Also, there may be other ways and decks to use, but IMO, I this is the best and how I would do it.
Have fun,
Gary