I have a 1974 CB550k. It’s a cherry 8,200 mile bike. Paint is near perfect, chrome is excellent and original exhaust. It appears completely original, but my frame VIN is 5,583 lower than the engine VIN. Frame is CB550 102 8xxx, engine CB550E 103 4xxx. Can this be the original engine? My ‘75 400f is only off by about 20 numbers. Thanks for any input.