This was just recently posted on the CR list:

"if it is a "Pro Miyata" as the one I bought new about 1980/1.Then it would be 600 AX with Dura Ace EX front and rear derailleurs.Also oddly enough 600 "arabic" dt shifters.The hubs are I guess normal 600 small flange with araya rims.The brakes are DC RGC sidepulls.
The "Team Miyata" from this period is all Dura Ace with a mix of AX and EX.
I hope this helps.I'll email some pics if you like.
Warm Regards,Harris Spracher
Waynesboro Va."

Just thought I'd share that.