Just curious, but when you take a project like this to a local shop to have welded, do you ask for their WPS? Wouldn't they have to prequalify for the car frame base material?
I was thinking it would be a good idea to take your battery-operated sawzall to the wrecking yard to get a bunch of car frame material to prequalify and test on. But if someone saw you cutting up a '59 Chevy frame, you could be in trouble plenty.
Bob