I had a yamaha ca-410 ingrated amp. Gave me 20+ years of fine service.
Had to give the volume and loudness knobs a twist every once in a while (with the power off of course) to clean the oxidation off the contacts.
Finally one channel gave up out on me. Wasn't worth fixing IMO.
If memory serves, the headphone out on this amp is pretty nice.
The CA-410 was a decent amp, but not the best yamaha made
at the time. If memory serves, it was only a few hundred dollars new.
Obviously a matching yamaha tuner from the same era would be
a good match. Maybe some midrange advent speakers from the
same era (Yamaha made some good electronics, but I was not
impressed much by their speakers)
Since you got the amp for free, I'd look for similarly priced components
to match with it (OK I'd be willing to pay a little for them...)
don't be afraid to mix and match components. If all you can find is a reciever many of them had decent tuner sections, and you can go from the tape out of the receiver to the tuner input of the yamaha amp. I did this with an onkyo, then later a sanyo.
Speakers are really personal preference. If your buying something old, listen to it to make sure they work OK. Speakers age much faster than electronics. But sometimes you can replace the drivers in speakers with good result.