Subframe seam welding

[makoshark]

I have decided I am going to not use the stock subframe I have been using on my car. I, years ago, had the seams stitch welded and the upper control arm mount removed, cut to Guldstrand specs and rewelded on. This frame was from a 68 I had years ago. I am going to dig out my original 67 frame and weld up the seams, possibly smooth it up with metal to make it look better. I am going to use the Ridetech Tru Turn setup as well as the ATS/Chicane upper coil-over mounts.

My question is, what is the best way going about welding the seams? I understand not to run full beads. Weld, say 1" seams, moving around to control the heat. Would it be completely necessary to make a jig to mount the frame to during the welding process or can I get away without having a jig. Keep in mind I am contemplating welding in strips of metal to make the frame not have the step appearance seen on the top and bottom of the frame rails.