The O)P's bicycle is pre-Technart, which is the name Bridgestone used in the late 1970s. Prior to that, they were called Diecast Frames, though the technology was the same (i.e, aluminum lugs diecast around plugged and flared tubes). The OP's bicycle has the distinctive diecast lugs and BB shell, though the head lugs don't have the faux windows of some later Technart versions.
Based on the serial number, the OP's frame was manufactured in February 1974, a couple of years later than my original estimate. Bridgestone's model names tended to be the same as the Kabuki models which they manufactured for the USA market, in which case the OP's bicycle would be a Super Speed model.
Selective photo assist...
