hey xander,
not much time to reply now (as richard had alluded to, i'm away from MI right now; currently in NYC), but i will say what i can. when you mentioned "he got attacked" was that from a previous attempt to put the fishes together, or did you try it recently?
that being said, i've kept a decent sized African with Cubans and other gars before with few problems...but that Cuban was only about 14" at the time. the active swimming nature of the bonytongue may attract attention as you had mentioned as well. given the size of the ABT and the much larger size of the Cubans, you COULD try it and see how things go for a day or two...i would suggest, however, since that other tank isn't horribly crowded for the ABT yet, to let it grow another 2-3" before moving it in.
ABT's are quite durable, so even if he got beaten up during the test run in the big tank it wouldn't be the end of the world (monitor closely), however, again, the size difference between your Cubans and gator vs ABT (former being the 2 most aggressive gar species) makes things risky.
hope that helps, if i think of anything else i will post when i can.--
--solomon
PS - what the heck is up with the 'gar media' forum??? interesting, but not sure i see the necessity...