If we assume this a Japanese frame (very high probability based on a 26.8mm seat tube and 68mm, ISO threaded bottom bracket shell) then the serial number format does match Miyata, who was a known subcontract manufacturer for Lawee and Univega. However, the serial number indicates a 1979 manufacturing date, which is after the Univega brand came into use.

As for the unique stays and lugs, I have not seen them on Miyata, but then any manufacturer will do whatever you want, provided you pay the premium.

I would not put too much stock into the serial for dating. Typically a subcontract manufacturer uses their own system and the Miyata manufactured Univega bear this out. So a Japanese system would have no continuity with the Torpado system, and the any resemblance to a sequence is probably coincidental.