Did you try this?:
http://67-72chevytrucks.com/vboard/s...d.php?t=685694
Also without the installed nuts you will have to use fender washers and nuts, maybe lock-nuts.
Unless you can use a long screw to hold a nut against the inside of the door skin (from the outside) and have a 2nd person weld it in from behind. Tough gig for the welder I would think.