That must be quite a generator to put out 250 Amps. LOL Remember that you will not be able to weld and supply power at the same time. You manually switch between the two usages.
I can easily see the need of a gasoline powered generator in a blackout. The cost of the gas would be well worth it. To run a welder on gasoline is OK when you are out away from power; but, not for continuous usage. Especially when your actual 'weld time' is just a small percentage of the time that you are 'welding'. You can always get a generator that will power your house and will supply enough amps to allow you to run your welder at the same time.