It is possible, but IMO more important than the total size of the tank, is the crowdedness of the tank. More powder blues in a smaller place increases your odds. However, this is obviously not good husbandry. So it's a risk, I think it a high risk.
I did get two to "pair" but they divorced within a month and in a few hours one nearly killed the other. I've quarantined groups of PBT in 4-5. I've had mixed success even with this in a 55 gallon tank. I've tried it with achilles as well. As soon as one of them appears "weak" the others will pick it badly and kill it quickly. They also single out the smaller fish.
I've read where people have kept several achilles together with what seems like 25-30% success in large tanks and 3+ -- but I follow up and hear that one or more have been killed out of the group. In short, I do not recommend this course of action. You'd need more than 5 in a tank that size to dramatically improve your odds, IMO. For my 500 gallon, 5 would probably be a decent chance of success, but I'd rather use that bioload for other fish.