There are some experienced welding guys (e.g., MARTINSR) over at www.rodder.com/rodderrap/index.html that might be able to give you the info you seek.

They seem to hang out in the Body Shop sub-forum, or you could set up a Take a Poll.

If there's a good sheet metal welder reading this in the Seattle area, I would sure appreciate some help setting up my little Hobart 135 Handler . . . .