Hammond Manufacturing, which makes a replacement line of transformers for Guitar amps, has released a model made expressly for the 2000S. Their model number is 290S2Z. It has the 55V bias tap and a 4 Amp 5 Volt winding for the rectifier tubes. Unfortunately , only a 117V 60Hz primary.
Link to pdf data sheet: https://www.hammfg.com/files/parts/pdf/290S2Z.pdf
That's good news for anyone who needs a replacement. I wonder if it is meant to be a replacement for the earlier Dynaco transformers, or the Schumachers? I'm sure it would work in place of both but I wonder which one it is emulating?
Greg