I would put the tag back where it belongs. The tag is protected when the seat is in place, and visible when the seat is flipped forward. Even if you didn't have the original tag, Kaiser Willys and most other outlets sells blank reproduction serial number tags, that can be either hand stamped as the original, or taken to a trophy shop to be engraved. The original body stamping should be on the driver's side toe board gusset, facing the back side of the inner fender. Good to verify the tag and body number matches. Also, the dash nomenclature will have the serial number stamped in it. Often these plates are missing.
The harbor freight automatic welding good works every bit as good as a professional Speedglass helmet that goes for $300. I have had expensive helmets, but they eat batteries. The harbor special works off solar power. Both are adjustable for different shades for different applications. MIG requires a lighter shade that a stick welder does. The autodarkener starts off clear, then within a fraction of a second, it darkens to the shade selected. You don't have to flip the hood up and down between arcs.
The welder settings depends on your material used. I use a Miler Matic 110 vac welder with .035 solid core Esab wire. The shielding gas is argon 75/25%. I keep the heat up, and adjust the wire speed to cope with the thickness of the steel being welded. The welder does well with up to 1/4" steel, but is at home working with sheet metal.