Most and best information I have ever heard is generator should be capable of 50% more power output that welder requires... Reason being that rotating mass of generator (rotor/armature) needs to be able to maintain inertia as generator bogs when there is high current flow when arc is first struck.... IF generator voltage drops to low it may damage electronics in welder....
IN reality you are going are only be able to use one 240 volt outlet of generator and largest output is controlled with 42 amp circuit breaker (at NEMA 14-50R receptacle) ....... And be aware the power output when running generator on propane is less that on gasoline....
Not knowing power requirement of Welder, but yeah it "should " be capable of running your welder.... IT may even be bigger (more expensive) than your needs.....