WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
Building, troubleshooting and testing of these amplifiers should only be
performed by someone who is thoroughly familiar with
the safety precautions around high voltages.
Study what you've drawn and you'll see the problems: grid leaks, grid stops, bias source. Also remember that your added adjustments can only decrease the bias voltage from its original value, so you need to start higher.