Correct bias for Mark IV with EL34

[tubularfluxus]

Hi,
On the PDF of the Poseidon board it says to bias EL34 in Mark IV as follow:
"Set each to 580mV using bias pot on amp"

I have calculated on this site https://robrobinette.com/Tube_Bias_Calculator.htm instead the following:
Tube: EL34
Plate-to-Cathode Voltage: 465v
Class AB Fixed Bias: 70% Max Safe Dissipation = 37.6 DC milliamps

Which value should I use? Wouldn't 580mv for each tube be 58 DC milliamps, so more then 100% dissipation?

Thanks