Assuming it has been transcribed correctly, I'm not familiar with that particular serial number format. Based on my experience with Asian serial numbers, my educated guess would be that it was manufactured during the last two weeks of 1986, which should make it a 1987 model. However, this is in conflict with the 1987 specs in the cycling magazine. Provided the components are OEM, the number of rear cogs would provide another clue. New 105 was 6 speed in 1987 & 1988, being upgraded to 7 speed in 1989. Component date codes may provide further clues. Regardless, the OP will soon have 10 posts, which will allow him/her to upload pictures, which may help to solve the issue.