The serial number format is not Fairly. They did not use an alpha character in the 3rd position. The other possibility that came to mind was Fuji, as they regularly changed formats and did use a similar format for a short period in the 1970s and 1980s.

The serial number suggests 1983 or 1993 and with a 93-3 date code on the post, 1993 would seem to be the immediate choice. However, had this been 1993, I would have expected some combination of dual bottle bosses, a pump peg, a unicrown fork and TIG welding. A check of my database revealed a 1993 Fuji Club (2nd from the bottom of the line) but ironically it was built by Fairly and had all the aforementioned 1993 features. Notably, the Fuji also had an extnded seat tube. However, the dropouts do look very similar. It doesn't match any catalogued 1983 Fuji.

The 25.8mm post is quite interesting as that is down in hi-tensile territory. Even the entry level sport models circa 1993 typically used butted CrMo. Tange would have used 26.8mm posts, so might this be a typo? It would be strange to utilize things like a cast seat lug and brake bridge on an entry level model circa 1993. Yet the fork does exhibit the lawyer tab retention holes typical of the entry level models. Curiously, the fork has eyelets, which the rear dropouts does not, suggesting the possibility that it does not match the frame.

Regarding the orientation of the brake cable ports, the production process likely would have been set up to install these prior to the frame build (due to the internal sleeve), in which case the tube could have be mitred and/or installed upside down. Rotating the tube 180 degrees would put the ports on the top and allow for a conventional, left side exit. However, is we consider 1983, a lot of the less expensive models, including the ubiquitous Dia-Compe 500, used a cost effective single casting for both front and rear brakes, which would position the cable on the right/drive side for the rear brake.

Had this been from a 1993 major brand, I would have expected some proprietary embossing on the lugs, stay caps, crown and/or dropouts. Of course, the other possibility is that it is 1983 and most of the characteristics do seem better fit this era, though internal brake cable were more rare during this period and it would appear to be OEM given the full length, internal sleeve.

I realize this post has posed more questions than provided answers but felt I should reply, given my mention in one of the posts.