Using a low-voltage switch in a high voltage circuit
The voltage rating of a switch is precisely about what how much of an arc it can break while it opens, and how much voltage it can withstand when open. Your switch must be rated for the maximum voltage that may appear across it.

This is true of any single pole of a switch, so it doesn't matter whether the switches you are using are SPST or DPDT. In principle, the pole-to-pole isolation could have a different rating than the contacts, but I've never heard of that being done for ordinary switches. Another place the voltage rating matters is the isolation between the contacts and the case and handle/button.

In your case, the maximum voltage appears to be 2/3 of the voltage applied to the ends of the circuit, or 114 V, since R1, R2 &amp; R3 operate as a voltage divider, but I'd want to choose a switch that can handle the full voltage in case something goes wrong elsewhere in the circuit. (Presumably your "R"s are actually loads more complex than a resistor on a circuit board, and so there's more opportunity for failures such as short circuits across any given R, increasing the voltage applied to the switch.)

There's another complication: switches have different ratings for DC and AC. If you apply DC, a switch with an inadequate DC rating is not guaranteed to successfully break the arc, even though it will withstand the voltage while open. High voltage DC switches are a somewhat unusual item (though becoming more relevant in this day of e.g. solar power systems). Apparently there might be electronic strategies to be able to use an only-AC-rated switch with DC.