Yours is a CB550F1-A. 'A' indicates USA market. Source: p.4 of your parts list: http://www.honda4fun.com/pdf_parts_list/pdf_spac550/CB550F_F1/CB550F_F1-1.pdf The year is completely irrelevant.
It is relevant, it is a 1976, as designated by honda. However, I have seen your previous posts and you are absolutely correct about honda prior to 1974. 1973 and previous years are designated as "sell date". So KO, K1, etc., is how to identify these bikes. We might say it's a 71, but in fact honda was all over the board with sell dates, release dates, but they actually were not model years.
In 1974 honda began designating official model years. And from 74 to 75, it was kinda a transitional period.
look at the 450 K5, is it a 72, or a 73?.....really neither, its a K5.
My 1975 550F is a F0........the 76 , technically is an F1, but not according to the honda guide....it's a 76..
The OP here could probably care less......it's a nice survivor.....real nice.