Shawn, are these the vent covers you are talking about? I was in the same boat .... been looking for originals to replace on my '77 CVX-20 as well to no avail... decided to go forth with these so I could keep my project moving forward. I just finished them, definitely not original, but what do you guys think?
It was very hard for me to accept the fact I was going to have to cut large holes in the top deck, but got up the courage and went for it. I think they turned out pretty good. They are kinda close I suppose to the old school 70's originals, but they do look very close to what is used on the later 80's models. You can still buy these new. They are unfortunately plastic, but easy to find a replacement if broken.