I recently did something similar with a large Phal of mine that was in a six-inch pot but growing over one side of it. I would love to let it do as it wants, but because of where it grows in my house, there's not enough room for all the Phals to grow that way. I found a slightly larger (seven-inch) pot that allowed me to shift the entire plant and root ball into a more upright position.
The one additional thing I did that I don't see on yours is I staked the entire plant to help keep it upright. That's just a temporary solution, I understand. Phals will do what they want to do, but this one has stayed more or less in the upright position for a couple months now. It seems happy and healthy and is currently in spike.
Good luck with yours!