Assuming your tapes are 2 channel 4 track (1/4 track) 7-1/2 ips recordings, you might also consider a ReVox A77 MkIV. These machines are quite good and in some instances a little easier to service in that the record amps and reproduce amps are on separate PCB's which can aid in trouble shooting. I have refurbed a number of these machines with good success. Of course in addition to replacing all the aluminum electrolytics, tantalum electrolytics, motor caps and suppression caps, the trim pots should be replaced as well as these get heavily oxidized over time and become difficult, if not impossible to readjust. The transport control relays should be checked as well and replaced if finicky.
Once all that is done, the mechanics should be gone over thoroughly. Motor bearings, guides, pinch roller and brakes need to be inspected and replaced or refurbed to insure reliability. I worked for ReVox back in the early 70's and have high regard for the design of this machine. Once refurbed, you should get another 30 years of service from it (assuming heads are not severely worn). They will cost much less than a B77. OTOH, if you are looking for a machine with balanced i/O, I would recommend a PR-99MkIII.
Once all that is done, the mechanics should be gone over thoroughly. Motor bearings, guides, pinch roller and brakes need to be inspected and replaced or refurbed to insure reliability. I worked for ReVox back in the early 70's and have high regard for the design of this machine. Once refurbed, you should get another 30 years of service from it (assuming heads are not severely worn). They will cost much less than a B77. OTOH, if you are looking for a machine with balanced i/O, I would recommend a PR-99MkIII.