Old sink, ptrap below floor, upsize ptrap?

[crazypipes]

I'm restoring an 1800's farm house and hoping to keep this really cool old pedestal sink in use. The way the sink is designed, there's no way to get the ptrap within 24" of the drain. The drain goes through a porcelain pedestal that has no cutout for a trap. It has to go below the floor to keep the sink.

The sink is pretty low by design, but the closest I could get a ptrap would be around 34" below the drain. I don't have to worry about inspections, this town has no zoning or building codes, but I do want to avoid siphoning of course. Would upsizing the ptrap to 2" (or heck, 3" could be done) help mitigate the siphoning risk?

 

[Tuttles Revenge]

I would use a 1.5" trap under the sink. If the trap is vented then siphoning should be negligible. Most of the use of a bathroom sink is just the faucet running which is a small amount of water which won't cause a large slug of water to rush down, which is the reasoning to have a maximum height for the tailpiece. But oversizing the trap creates a situation where the flow from the sink doesn't scour and self clean the trap.