That is a big Miyata with a stand over height of 34 1/2" it's probably a 25" frame, maybe 23". How tall are you? You would need to be 6' or taller to ride it comfortably, YMMV. You can see the seat post is shoved all the way in since the bike is too large for the current rider.
http://1.bp.blogspot.com/_whtVpXkKwl...0-h/img042.jpg
FWIW, the bike is a 310 and has double butted cro moly tubing, hi-ten fork and 27" wheels. The 312 was made in 1988, (maybe other years). I have had both of them. If the 310 fits you and is in great shape it might be a $200 bike. Depends on your location. That would be top of the market where I live but it's definitely worth a look. Just make sure the seat post moves up and down.