I agree with
SilverArowanaBoi
in general cichlids and lungfish would not mix well. I haven't had any experience with lungfish except Australian Lungfish but from what I've read most Lungs can turn suddenly, literally go from peaceful to suddenly buting a fish in half. Other than that, many cichlids will be attracted to Lung appendages and pick at them. Then there's feeding, cichlids are fairly aggressive eaters while Lungs can be slow to locate and consume food so the Lung can be outcompeted for the food and slowly starve. That's definitely been my experience with my Australian Lung. My Aussy is very slow to find food and in a competitive environment I was forced to tong feed him or hand feed while trying to keep the other fish at bay.
Also as SilverArowanaBoi said most gars aren't all that aggressive except Gator Gars, predatory yes, aggressive not so much. They can also be slow to feed. They find food fast but Gars such as Florida's at least when it comes to pellets can't get many when competing with cichlids as they just inhale pellet after pellet. Gars do make good tankmates for at least IMHE Aussy Lungs. They both inhabit opposite strata of the water column in the aquarium. Making territory an unlikely problem as well as feeding. Gars can feed off the aquarium substrate but it's not their preferred, feeding location and vice versa is true for Lungs. So feeding floating and sinking foods easily handles that.