A 55 is not big for a 10" territorial cichlid. I think it will do if you take good care of it, 75g would be better once it's fully grown.
There are some ways to make your fish grow faster.
1. Plenty of filtration (15-20x turnovers per hour).
2. Diverse diet (bloodworms, pellets, market shrimps etc)
3. Powerfeeding (3-5x a day, make sure no food is left behind)
4. Large weekly water change (40-70% each week, depending on filtration).
5. Higher temperature (=faster metabolism, keep the temp at 28°C)
This hobby is all about patience, he will take some time to reach 10".