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.
No idea about the sockets but you could always not use any . I suppose you could punch a hole in the chassis and clamp the base of the valve with a capacitor clamp then add connectors to the valve pins