k-member reinforcement
The plates from Firm Feel need some trimming, they aren't a perfect fit by any means.They also need some shaping with a BFH to curve them to fit better. As far as warping the K member by welding on the reinforcements, you'd really have to work at it. I mean, you'd have to heat the ever loving crap out of the thing in order to warp it. A jig isn't necessary, I've fully seam welded and reinforced two of them now without any issues at all. Same rules apply as for welding on anything, move around and let the other sections cool in between sessions. When I did the seam welding I would do a 4-5" section and then move to the opposite side and do the same thing. Obviously it would be a good idea to make sure the K is straight before you start reinforcing it. I also went over all of the factory welds, more than a couple of them were cracked, including the steering box mount. The one on my spool mount K was cracked to the point that the steering box moved when you turned the wheel.
As far as the plates, the big triangle goes on the bottom of the steering box mount and gets welded to the steering box mount, the engine mount plate and the back of the K frame. It fits better if you bend it to fit the lower curve of the steering box mount. The half moon little strip I didn't even use, it goes in the narrow gap under the steering box mount, in the curve that starts right at the end of the triangular reinforcement piece. I was able to weld the steering box mount directly to the K there with two passes on my MIG, so I didn't use the little strip. The half triangle, half round piece goes on the front of the steering box mount, but it has to be folded at a 90* angle. Also, when you weld that one in check the steering box clearance. If it sticks up to high or out to far forward it will hit the box. I just made templates for mine, maybe these pictures will help a little. I should have taken pictures when I finished welding, now that its installed in the car you pretty much can't see anything.