Your numbers of 800V @ 416 mA, calculated for the trannie are correct. In addition, they state that on 60Hz power, the actualy VA capacity is 10%-20% higher, so you should have plenty of power "overhead", as the circuitry should draw around 200 mA average, for both channels.
First of all, make sure that the chokes can handle the high voltage, and not suffer from winding-to-core breakdown. Ditto for the 6D22 filamant trannies. These trannies are usualy hi=potted at 1500VAC / 2121 VDC, for dielectric withstand, but this is done at low current and for a relatively short test time.
The 158Ms are rated for only 400VDC:
FILTER CHOKE, OPEN BRACKET, HAMMOND, 10 H, 100 mA
Specifications
Rating: 10 Henries, 100 mA
Max. VDC: 400
Resistance: 262 ohms
Mounting centers: 2.81" U-frame
Weight: 1.3 lbs.
(I just thought of an easier simpler method, so I just edited out a few unnecessarily detailed and lengthy paragraphs)
Use the circuit that you already have, just connect the Secondary's CT to its own C-L-C or C-R-C filtering, in order to generate the half-B+ (450VDC) power for the driver stages.
The power trannie I had in mind was the Triode P782 or the Hammond equivalent, but the Antek toroid should be perfect, and less costly, and they do have available some even higher current versions. The 813s will need some seriously hefty filament power as well, either Hammond or Antek should have something usable here.
BTW, I just ordered (on 6/21) an Antek 4T360 for some future "ST70" project.
/ed B in NH