I have successfully kept Chocolates and Parrots together for years. Keep a minimum of two sizeable hiding spaces for each fish in the tank, and when they get into a territorial mood, you have nothing to worry about.
Parrots and Chocolates both enjoy hiding places.
Parrots dig A LOT! Make sure to give them ample piles of substrate to play with. They'll stay so busy digging, they'll ignore the Chocolates for the most part.
Chocolates only seem to be aggressive when hiding in their home, and another fish tries to get near it--typical cichlid behavior.
Either way, I think the combination will be great, and both are incredibly slow growing, and long living.
You'll not need a larger tank for a long time to come--that I can assure you.