[Magnavox300]

I am restoring a Zenith phonograph amp and replacing everything in it.
The schematic shows the values of the ceramic disk caps, but not the voltage?
How do I know what the .470, .0022, and .0047 disc voltage is on these?
I thought of just going with 250V, since they are for the potentiometers.
But even the .01 discs do not show the voltage value on the schematic.
Anyone know?