The UTC A-25 15K:600 (and lower) plate to line transformer is rated for 8mA unbalanced DC and output level of 30mW.
So it has some tolerance to dc current flowing thru it.
I guess you could use it in a single ended or a poorly balanced push-pull topology with no dc blocking, within those limitations.
Without wishing to be sound offensive,
using a UTC A-25 on some old voltmeter amp is kind of like casting pearls before swine
That traffo is quite sought after and fetches a good price.
Sell it, buy some cheaper parts and do whatever your experimental heart desires!