I don't understand why you wouldn't just use a multi-volt ballast to test the fixtures. They can take 120V through 277V and 50 or 60 Hz.
He's probably testing the ballasts!
Nobody is going to make that transformer as a standard, there is no use for it (in enough volume to make it worth building). You are going to either need to have a custom transformer made for this, or build your own system using something close, then adding buck-boost transformers to get to the odd voltages.
For instance use one of these multi-tap transformers
, boost the 240V up to 277 and and buck the 380V connection down to 347V
Or like I said, call someone like these guys
to make you a custom transformer. A one-off like that is going to be expensive though.