I have a 57cm square (I think) '87 Cdale SR500, the year they had the optional "custom graphics" so it's super rare valuable, dontcha know?

Let me know if you're interested, I can get you accurate measurements and much better pics. (Shown as found, it has been cleaned and touched up since then) I have the correct saddle for it, new cable housing and such to return to original. Except maybe the triangular 105 pedals.

I was planning on finishing it and keeping it on hand for a guest ride, but your Miyata is near the top of my list.