This is a good resource for finding your ideal plate current for most tubes. I picked al EL34 here
https://robrobinette.com/Tube_Bias_Calculator.htm
Class AB Fixed Bias row at 70% is what you're looking for
This is what it's doing :
you're looking for current in amps
(Current in amps) * (B+ Voltage) = (Dissipation )
EL34 dissipation is 25 watts
Shoot for 70 percent of total dissipation when biasing power tubes in guitar amps
(Current in amps) * (414v B+) = (25 watts) *.7
(Current in amps) * (414v B+) = 17.5
17.5/414 = .0423
Current in amps = 42.3mA
Same procedure as what you did with Uncle Doug, but a different way of looking at the math.
25 watts of power is how much electrical power the plate can handle before it burns up because of heat. With more voltage on the plate, it has to flow less current in order to be safe inside. This is why you have to adjust bias with different plate voltages. 70% lets it run for long periods of time without pushing the limit of how heat the plate can dissipate.
Glad you got it sorted out. Enjoy your new amp! I'm sure your neighbors will too