In agreement with you about Namor being a member of the Avengers.
I remember reading about it in Avengers #262 during the '80s.
Truly a momentous occasion that I'll always treasure...
This was one of the greatest Avengers lineups ever. Namor as an Avenger was great! Having Big John Buscema on art made things even better even though he used the weird triangular head in his Namor this time instead of his bullet one which I prefer!