The lions should be fine together, but even one volitans in a 72 gal is one volitans too many once it reaches adulthood.
Like many folks, I used to think that fudging them into a smaller setup wasn't such a bad idea until we upgraded ours into a "proper" tank (it has outgrown 4 setups, which was the plan) and it has really changed now that it has some "real" room to move around and stretch out.
HTH