Re: 1969 6hp complete powerhead.
I suspect that a '69 head would probably fit at least a 1965 - 1976 6 horse. The 6 continued through 1979 but switched to CDI ignition for 1977 (there may be a change to accomodate the CDI ignition).
I don't have the link handy, but BRP has an online parts manual going back to 1968. If you get the URL for the link (somebody should have it), spend some time comparing part #s for different years of 6-horse. If the #s are the same, you have your answer!