Honda-SOHC

Hi everyone, first post! This bike, cb650, has been in my family since I was at least 4 years old and now finally I have gone from the small child pillion passenger to being the 40 year old rider who passed his test two weeks ago. Having emigrated with the bike from the Netherlands in 1993 the dvla have the bike registered in 2007 as a 1981 model although the chassis is RC03e2005360 which at a google guess shows it as being 1979. Is 1979 correct and was the import registration flawed or is it in fact a 1981 bike? The DVLA and I would both like the V5 to be accurate and the plate to be from the year of manufacture hence the question