Long-time rider, first time poster on this forum.

I love my vintage Bianchi & Peugeot bikes, but I haven't had a vintage Japanese bike in my collection since I sold the Miyata 1000 years ago. (Yes, yes... I know I shouldn't have sold it, but the sale helped pay for an old Porsche 911 back when they were still reasonably affordable, so maybe the trade-off was worth it.)

So, I've decided to build a vintage Japanese tourer using parts (SunTour, Ukai, etc.) I have from old Motobecane-France, Fuji and other projects. I could buy another Miyata, but I have all these old parts...

My question is the frame. It is a rather heavy 58cm straight-lugged steel frame with no brazed on stops and a four digit serial number - 8914 - on the bottom bracket and no other identification. I know the frame dates from 1973 or so, so maybe the "8" indicates Japanese year Showa 48? And yes, it is definitely an "8" and not a "B".

So maybe a non-letter ID Bridgestone or Miyata?

Thank you in advance for your inputs, and yes I will be posting photos when I reach the required number of posts.