Since the transformer is on their side of the fence, we have little to say in the matter. They ultimately found one in one of their 'yards' a bit over 50 miles away and got it to us real fast. It is about 35% larger in capacity than the failed unit. Since it was sitting in the weeds idle, I suspect it is also used or reclaimed in good condition from a different customer upgrade.
I do not think a larger unit will hurt us any. There is the LOAD RATING or factor to consider. If all the connected loads at full draw were to be on line at one time, we would have gone beyond the capacity of the old transformer.
As to more power for the trolleys, the short answer is NO. We have two substations powered up and in operation and their limit is what can be delivered to the overhead. Feeder wires and a third small sub, perhaps closer to the east end, would be needed to have more power for equipment. We have the capacity for 2000-3000 amps in the trolley wire, divided among two power districts. Something no other preservation site can come close to. A larger capacity on the primary side will not give us more than the subs can produce.