Cost to convert from gas to oil?

I’m in contract on a house with an ancient oil-filed steam boiler (83 yrs old!). I’m planning on replacing the damn thing as soon as I move in.

My inspector said I should go with gas. (The house already has a gas main for the water heater.)

Seems like everybody has an opinion on this issue. In terms of capital costs, how much is it going to cost (ballpark) to replace the boiler with a gas furnace? I assume I can reuse most of the radiators and plumbing, as long as I don’t want to convert from steam to hot water.