Honestly, I'd see if it eats. Too large of an enclosure isn't the biggest problem with a ball python, security is. A bunch of tight hides, make sure the humidity and heat are where they need to be, and see if it eats.
And, yes, a tub is superior for ball pythons. It offers a sense of security and is very easy to maintain for a keeper.
I was keeping hatchlings in an adult tub. I put a dinner plate in there for them and most of them were fine, although I did have a lot of overflow and needed to put the rest in smaller tubs.