This set has a push-pull output, so you need a xfmr with a center-tapped output. Otherwise, not too critical.
You can leaf through the AES and RadioDaze catalogs to find universal types or ones recommended for your specific output tube types.
I seems that somebody canibalized your xfmr. Perhaps the set has another problem, too. Check the power transformer - that is more expensive than the audio xfmr.