Air Gap intake back form media blast.. clear.. paint or run as-is?

Whatever you decide @CudaChick1968 can give you ideas as to what makes aluminum resist the elements (as in longevity) from a professional standpoint.
Aluminium gets a thin oxidation layer on it almost immediately that prevents further deterioration. This also prevents glue products adhereing well. There is a surface treatment for glueing from I think West Systems. Paul Lamar of rotaryeng.net recommended it. He is gone now and I am not sure what his son is doing with that site.