Marshall 10 watt combo clone

[Bushbaby]

You will have to excuse my extreme ignorance here. If we take a transformer with the following values do I take it that I should have the caps at a rating of 300v (to allow for rectifications) OR at max main voltage of 240v?

Mains 10-0-200-220-240 50/60Hz
Full Wave rectifier 300-0-300 VRMS 125mA DC
Heater 6.3 Volts Centre tapped 3.1 Amp
Heater 6.3 Volts 1 Amp
(Suitable for Mullard 5-10 mono amplifier)