Making a welder from an alternator and engine

[sanddrag]

I read on this page that you can make a pretty decent TIG welder with an alternator and electric motor. My question is, can I make an Arc/Stick welder with an alternator and a gas engine? Does arc welding put a higher load on the electronics (alternator) because it is more of a direct short? Will it burn out the alternator, or will it be okay? The engine I have is an old 3HP Briggs horizontal shaft lawnmower engine. How much of an alternator (how many amps) could I run off of that? The above linked page recommends a 5HP electric motor for a 130amp alternator, but electric motors and gas engines have different torque characteristics.

If this will work, how much do you think an old alternator will cost and where should I get it (U pick parts maybe)?

Thanks.