Speaking as a person who is 40 years old and currently owns a stock car 2 years older than that '69 Camaro, I think they look fine, and the primer doesn't bother me. The car's a work in progress, obviously. If I was still working on it as well, the last thing I would do is paint it. Final paint is always the last thing you do - why risk the paint job if you're still swinging wrenches on the car?
It's not like he has some crappy molded black urethane Wings West kit stuck on his car because he can't afford to paint it, that's been on so long that it's been curbed twice and will need to be replaced before you can paint it anyway. The car is in grey primer, all over. First off, there's a historic precedent to that: finished hotrods from the '50s and early '60s were often left in primer as the finish coat and never painted a color. Also, among the retro rodders right now "suedeing" is popular, and has been for several years: tinted primer with flat or semigloss clearcoat over it to create a smooth, low-shine finish.
Camaroboy, you do need to rig them up so all three lamps light up in each taillight, though, not just the middle segment.