Polypterus is a good suggestion. However, not the lung fish. Every So. American lung fish I had were very aggressive towards All other fish-including other lung fish. I always had to keep them alone in their own tank because they would Always attack and kill Anything in the tank with them.gars do not need driftwood, in fact it just impedes their swimming and is unnecessary.
congrats on keeping your FL gar for 11 years! that is quite the accomplishment and the fish is looking good. for tankmates i would suggest polypterus species and other gars...south American lungfish can also be a reasonable tankmate. good luck--
--solomon