We'd need a slightly special OPT, for running E-Linear, say 20 and 30% taps on the plate winding. Pentode input valve, rigged as a pentode with a super g2 supply, say a 12BY7 for the 813, or a faux pentode made from a pair of 5687 sections ( a.k.a. cascode ).Say 700V B+, 6k/120 mA OPT and we're off to the races.
an 850-0-850@ 200 mA, 10 amps of 2.5 volts for the pair of 866's plus 10v/5A for the 813 filament and we're off to the races. don't forget about a good PS choke and some 440vac motor-runs.
regards,
Douglas