If you're talking about mine, it's a 60cm, so it's too small. Close call!

Based on a spec sheet that used to be posted on the Miyata/Specialized yahoo group (which seems to have disappeared from the file database), mine was marketed as an '83. I think yours may be an '82 or earlier. Mine has a Sugino AT crankset and Suntour Symmetric top-mount shifters. It is in very similar shape to yours, hardly ridden and all original, though it did suffer some scrapes to the paint as the result of poor storage.