The serial number indicates that the frame was manufactured during weeks 3-4 of 1988 by Giant of Taiwan, a known source for SBI. It's definitely a 1988, mass production model. C801 is the part number for the bottom bracket shell. This is a more basic shell than that used on the Allez and is consistent with the Sirrus. The fork crown also supports a Sirrus. The red herring is the brazed-on front derailleur mount as neither the Allez or Sirrus, which were SBI's only steel road frames that year, had this feature. I'd say it was 1988 Sirrus with an owner added front derailleur hanger and a re-paint.