Here are the notes on replacing the interstage transformer. On a radio similar to yours, I used modification C:
http://www.philcoradio.com/tech/audio.htm
It kind of reminds me-while most radios of this period are set up like yours, with the last two stages transformer coupled, I have an American Bosch radio from the same period that is entirely resistance coupled. Maybe Wa2ise can explain the advantages/disadavantages of these circuits.