Unterhausen, the progress of finding and restoring this $25.00 frame and fork has been one of several posts, from beginning they include:

Help any information on "Erba" bicycle signed by "H. Hagiwara"?
Help, Any information on this H. Hagiwara Frame/Fork?(1 2 3)
Restoration: H. Hagiwara "Erba" getting ready for the painter/decals.
"H. Hagiwara" Erba-back from the paint shop(.1 2)
H. Hagiwara-"erba", the restoration is done.
“H. Hagiwara”-Erba-final changes.

There are many pictures in these posts of the found frame/fork, through several stages of restoration and component selection to this final addition of a mock race number card. The only last last thing I might do is to have a pair of period correct (mid-70s) vintage Mavic tubular rims and SunShine Pro-Am hubs built with the selection of a 23mm tubular tire, which would have been the choice of a racer during this period. Hope this helps, if you can't find the picture you would like to see I can always take a close up of the seat cluster, just let me know.

I have also wondered if Mr. Hagiwara of Alps fame could have been the builder, efforts to reach him in Japan after contacting the Japanese consolate office sadly failed.