Sorry Guys, I feel like I am hogging the forum here.
Further checking tells me that,the data/specs, barring the Htr. Specs at 2.5 Volts for the 2X3 and 5Volts for the 5Y3, both of those two tubes are alike. They both draw 2 Amps. and safe operating voltages (higher than I first thought) are also identical. However, as I said on my first post above, 350 volts, Plate(s) to Centre-Tap on Transformer would be about the normal operating voltage on your set. Which at the input to your filter choke/field coil, would be around 250-270 volts DC. So use the Data supplied at Frank’s Site, or any manual for that matter, for the 5Y3 as your reference. and you will be in save water.
Ralph