Hi, Jeff. We had to do the same transformer installation when we had to replace our old IR oven used to solder printed circuit boards. The new (to us!) oven required 480V. and could not be converted to 208V. The electrical company next door did the work. They had to derate the transformer about 20% when it was wired backwards. Works fine, but does get warm.
The transformer is connected to a 150A circuit breaker which we used as a switch to turn the transformer off at night and on weekends. One morning only 2 phases turned on. Turns out a fuse on the electric meter opened up. It is a quick-blow, silver fuse. Next week the same thing. So, the electrical company said to just quit using the CB to turn off the transformer. No problems since. The heat is nice in the winter, and not noticable in the summer.
I think the transformer cost us $75.00 plus shipping from Portland. There are lots of them available used and just laying around in elctric company warehouses. Don't buy a new transformer, they are quite expensive.
Good luck.
Paul in Redmond, OR