It should be fairly easy to fabricate a silicon diode rectifier, with a suitable resistor, in an octal base as a substitute for a 6X5. This has the additional advantage of taking some load off the filament winding on your power transformer.
And if, for some reason (like show-and-tell at a radio gathering) you want to use the real 6X5 tube, all you have to do is unplug the diode base and plug in the tube.
At one point or another, commercially made diodes-in-a-base were available, and may still be as far as I know.
I think you are better off making your own as you have more choice as to the value of a resistor you want to use.
Best wishes and happy holidays,