These hybrids are called "Black Forest Conures"... in other words, it has already been done.
If it's a conure, it can hybridize with any other conure. Doesn't matter if it's a green cheek and a nanday, or a sun and a golden... they can hybridize. The larger conures can also hybridize with mini macaws, amazons and caiques.
Not sure yet if the Pyrrhura conures can as well...
Possible, but only ADVISABLE if...
You're an experienced breeder, or have one close at hand, or a certified avian veterinarian on call... and... you have a placement or plans for the babies.
Breeding birds is a very difficult thing to do well, and so so so many things can go wrong... egg-binding... parental aggression or neglect... nutrition/feeding problems...
Maybe you were just asking out of curiosity. If so, I'd be alert to the possibility of breeding, which might get you into something you don't really desire?
Ar you sure they're male and female?