On the googled picture, I just posted what came up and looked like my model, I was more curious as to the type of seat it had since I know that my seat is wrong. If these are mid-60 models, then I suppose the reflectors could be correct, mine didn't have them and I guess they could have been added too.

I have no idea, but I would guess that Miyata probably had a 'if it's not broke, don't fix it' attitude in their bicycle manufacturing, especially after the war. If it is a 60's model, I'm thinking it's a model that Miyata produced for many years and just didn't change all the tooling. That would account for some obviously old patterns and styles combined with some newer materials. But I'm guessing.

Dave