I was under the impression that you were building the entire circuit from scratch, not that you just needed a power supply.
In any event, this is the tube era and that means you pretty much have to build one. You basically have to build a topology like the last figure on the right, here;
http://www.hammondmfg.com/pdf/5c007.pdf We need to figure out L & C and whether or not you may need or want a regulator The 315 is a bit high, I think for that regulator circuit. You can get a 360 V transformer, but not a 350 V transformer. I corrected the earlier mistake in my post.
The PS-1 manual that I am reading suggests using a full wave choke input supply where:
(60 Hz) L ~= Vout/Iout (mA)
(50 Hz) L ~= 1.2 * Vout/Iout (mA)
Iout = Iac/0.707
Vdc = Vac*/2.2 - Vdiode-Rinductor*I2
* Entire primary voltage
Not sure if L is in Henry's or mH; Although probably mH.
But they do suggest using a 115 to 230 transformer in a rectifier/diode combo. They say that 230 VAC non center tapped xformer should result in 325 to 340 VDC, So, you might be able to get away with an isolation transformer..
The PS-1 MIGHT work at 315 V with some component changes.
What's your mains voltage? 230? 240?