My 1987 Miyata has cast seatstay caps that say Miyata on them. I've seen those same rear rack mounts on a bianchi randonneur from the early 1980s... but that bike didn't have low-rider braze-ons. Might be worth offering 40$ if it's really been for sale since the 5th of December... might make a neat "gravel grinder" assuming you can get the fork fixed cheap.