Coming in late :-)
There is no thing as a "bias supply" in a st-35. It's a cathode biased where all 4 tubes share one 100ohm
resistor. And there is a very good reason for that.
I would recommend to get a build manual for st-35 ( it's available at this site ) and start to
revert to it's factory configuration.
Apart from D. Gillespies EFB mod there is nothing done that improves the st-35 ( in my opinion),
reverting it to factory will only improve it.
That said, you might want to leave the B+ supply with it's separate caps as-is, it seems to
be a functional equivalent ( i have not looked that deep, but with the manual you can examine
The one thing added in this amp seems to be the power switch , an item left out by some
reason during design. Keep it if you like, i prefer ( again a personal preference) to remote-control
poweramps with a solid-state relay. YMMW.
The st-35 is generally considered as the crown on dynacos work, it the last tubeamp designed and
it has the best sounding transformers, but and that's the down side, it need sensitive speakers.
It's also one dynaco that uses current production tubes, and it run's the tubes very conservative, there is no hitted dangers, and any brand of correct type will do well.
EFB is worthwhile to look at , see tronola.com http://tronola.com/html/ps_mods_for_st-35.html
for a discussion of the st-35 and what possible with modern components.
Congrats to a very fine amp!