You can swap some breakers around and balance the service once you get real 3p wye in there.
You can get a head start by going in with your clamp when they are running their normal load and tagging the current on each circuit. Then you will have a starting point for the rebalance.
We used to have to do that in computer rooms sometimes because each machine might have significant single phase loads and the luck of the draw might get some unwanted imbalance.
