Black wil be very hard to maintain, you will always be working on keeping it clean and it will show EVERY flaw. Red is easy to maintain and is one of the hottest muscle car colors. There is a reason why the aution houses call lots of cars that pass thru "resale red". It sells. I have two red cars, one black one (Mercedes, had no choice) and my Calcutta Russett Metalic AMX. I will never have another black if I can help it.
I am currently finishing up my 74 Javelin I purchaced new. Painted it to the original T/A Red. Loved it in 74 and still love it in 08. I have posted many restoration pics under WV74jav.