[Gonset] Guessing Transformer Specs from Schematic?

[doc]

The Gonset G77A manual & schematic file is here
(both pdf and djvu):
http://bama.edebris.com/manuals/gonset/g77/

The Modulator/Power Supply circuit description says
it is a grid modulated design.

The modulation transformer is across the plates of
a pair of 6GQ6-GA's and 250V is on the center of the
transformer then up to the grids of the single 6146.

Or so I think I read the circuit diagram.

Can someone guesstimate the approximate values of
a transformer in this configuration?

Thanks! & 73, doc kd4e