Look up the amp draw on the welder on the data plate, i.e., 30a at 240v or something similar. If the welder delivers that without being firewalled, it should work. Forget the 230a on the welder side, that's output at a lower voltage than 240v, perhaps 24-36v or thereabouts.

You need a little math here. 30a @ 240v = 7200watts (watts = volts x amps) on the supply side from the genset or the wall outlet. Do not firewall the genset either. If you need 7200w, buy 8000.

Also, you can operate the welder at lower amperages on a smaller genset, but you need the current draw figures at the lower welding amperages to calculate how much smaller you can go. 230a is for fat, fat, steel, so a lower working amps will probably work just fine...