I have a Sekai 4000 Professional which I purchased new as a frameset in 1983. The serial # is M8M 22913. It was black when new, has Shimano SF vertical dropouts, Champion #2 Tubing, Heart cutout lugs, brake bridge diamond reinforcements and a full wraparound seat stay attachment. It had the green Champion tubing sticker. Is this a 1978 Miki produced frame?