My 67 had 70's style mirrors when i bought it. Much better visibilty but i wanted factory mirrors. I picked up a 67 remote for drivers side and the round 67 passenger mirror from a firebird only salvage yard. At the time i didn't know there was a difference, luckily the owner showed me the difference and didn't just hand one over that would work. The vent post doesn't obscure the mirror as long as you have a 67 mirror. Visibility isn't great but you get used to it. Now it looks as it should. If you don't have a 67 mirror i would think classic industries or year one can hook you up.
Btw; Thats a nice clean looking 67.