That serial number format typically surfaces on Shogun. It should be a 1979 model based on the serial number, in conjunction with the long spear points for the lugs. That would be too early for 1st generation Shimano New 105 (aka Golden Arrow), which was introduced in 1983. However, it would be appropriate for Shimano 600EX. I've seen both Shogun 600 and Shogun 700 from this era with Shimano 600EX.