I agree with bzzzzz. Wiring in older homes is often marginal and it isn't a good idea to run a machine on a circuit that is 75% under-rated. 120 volt machines are low-end as it is and soon you'll be running the machine at maximum. And you don't always know how many other appliances are plugged in to the same circuit, so you could be overloaded before plug in your welder.
Usually, it is not too difficult to run a new circuit to work areas. If you aren't familiar with electrical work, you really should hire an electrician. I believe the statistics show that more people are killed with 120 volts than the higher voltages, and that is mainly because we all take 120 volt circuits for granted.
Chet Guilford