I built my first 8.50 cage this year. I also used an S&W kit, Chromoly to boot. The best call I made before the build was to our division NHRA chassis inspector. I had that guy on speed dial and he was happy to answer all my questions. By the time he came to certify the cage it was a matter of formality. No drama! As others have already noted, anytime you can tie directly into a frame component the better, including the lateral bars (referred to as D bars in NHRA general regulations). Cheers!