Thanks for posting the photos.
Here are the components from the bike that I noted.
Sugino VP crank.
Sugino bolt in the lug at the top of the seat post.
Shimano Light Action rear derailleur
Shimano Light Action M5 downtube lever shifters (in the frame)
Shimano front derailleur
Dia Compe side pull caliper brakes
Dia Compe brake levers
Hsin Lung drop bars
Freewheel has 6 gears
Crankset has 2 gears
Either the front or the rear wheel is not original. I suspect that the rear wheel is original and the front was changed at some point.
Front wheel:
Sunshine 4345 front hub
Wolber rim (T410 Alpine, chrome magnesium) hard anodized,
700 x C200 tire
Tube has a presa valve
Sunshine quick release levers
Rear wheel:
Suzue 7 L rear hub
Araya 27 x 1 1/4 rim
27 x 1 1/8 tire (tire size is not the same as the rim)
tube has a Shrader valve
The derailleur cables pass under the bottom bracket and go through holes in the bracket.
From looking at some Nishikis, the lugs look like they might be the same. I don't know if Nishiki made the lugs on their own bikes or if they sourced them from another manufacturer and if so whether other bikes would have used the same or similar lugs. Or maybe I just haven't looked closely enough and they're not the same.
The forks and head tube look like they might have originally been black but were spray painted silver to be closer to the colour of the frame. (There might have also been black on the first 10 cm of the frame near the head tube.)
Although it's far from being in pristine condition, I was thinking of fixing it up. Other than surface rust, it seems to be more or less functional. I think that I might only need to replace the cables and a few spokes, de-rust the chain (or put on a new one), and put on new pedals.
I'm just wondering what brand it is. I was thinking that maybe it's a Nishiki. After a bit of searching on the internet, I've seen a few that had most of the components that this one has. I'm not sure about that serial number though. I thought that it should have a second letter after the W if it's a Nishiki. Unless the second letter was stamped in the cable groove. That would be weird but I don't know how diligent people were about looking at placement when they stamped numbers on the bikes (or even if there was variability in where it COULD be placed).
Anyone recognise the brand and model based on these details?