The power transformer in my opinion is not ideal as it only has one secondary winding with about 230 VAC - so it will not give you the desired output voltage of 300 VDC even when used with a silicon rectifier. Furthermore it has no separate winding for the heater of a directly heated rectifier tube - so you can either use silicon rectifier diodes or an indirectly heated rectifier tube in a hybrid configuration with two more silicon diodes.
If the power trafo gives a problem too, it's like this.Soft recovery diodes will do very well.
This is exactly as I think it should be. To be sure, please check continuity of the two unused solder lugs - the 3rd from left (assumed screen grid filter choke part of primary) should have connection to #1 and #2 and the 4th from left (assumed feedback winding) should have connection to #5.Is this correct