k-frame strengthening

I just finished doing this, basically just weld all the seams solid that are spot welded, most important is to box the steering box area in, I cut some 1/8 in. Plate to fit in the open areas on both sides, this will keep that area from flexing. Some people add washers to the areas where the lower control arm bushing would ride and also where the strut rod bushing bolts, make sure the washer is not thicker than the area that already protrudes at the lower control arm. I also added a skid plate underneath.

x2
also added some round bar to reinforce the arches and a tow hook.

there are some pics if you follow the link in my sig

also firm feels site will give you an idea as well.
http://www.firmfeel.com/reinfkfram_a.htm