If you want to put the focus on the lions, and are willing to commit to feeding the lions, even live if necessary, you can have any lions you want. The volitans are the most agreeable and the fuzzy being the most agreeable dwarf as far as feeding goes. If you click my name and "find all threads", you'll find alot of info on feeding lions and nutrition. The pebbletooth eels work well. The damsels may become food but are also elusive enough they may survive, or at least for a while. I've kept clown triggers with volitans on more than one occasion and several years or more with no issues. Be reminded all fish are individuals and there are many variables.
In a large community tank I do lean more towards recommending the volitan, russell's, or miles. Regardless of others success in getting the dwarf and medium bodied lions to eating dead food, it is never a guarantee. And very rarely do those succeed in getting them to eat the proper dead foods or the amount needed for long success. So trying to feed live food in a large community tank gets very challenging, not impossible, but very challenging. I do have tricks, but it does take effort, it's not just dropping food in the tank. While you will still need to target feed, the larger lions like the volitan take to dead food pretty easily, and will accept the variety of dead foods and eat the amount needed for long term success.
In a 300g you could keep 3 lions of your choosing easily. Lions are actually more social than many think, males may have angst with each other, but in your size tank I don't think there will be issues that get out of hand. Your scape sounds good, lions will enjoy caves and vertical rockwork for perching. While happy lions are more active than many suspect, they do spend alot of time perching, so with multiple lions you do want to provide multiple spots. Here;s my current venom tank.
