Can you recolor the covers to match the armrests or rear shelf, perhaps, like it's a GM option? Of course, not much you can do with non-matching black belts, especially if fronts are good and don't need replacement.
One problem I have, ongoing, is that the tan belts I restored don't use webbing that meets local standards, even the new Morris and similar don't if you get someone picky. Many accept it as a classic and they function as they should, but not all. That's not the main issue, the problem is that no one here has come up with a tan or gold belt remotely close that I could even reweb them with. If that were the case I'd possibly consider a rear retracter option, knowing I'll never have passengers, but you never know what requirements they may think of, the rears were already a decade behind others when new.