When I did the disc swap on my New Yorker I ran into that problem. Turns out I had the calipers front mounted like the Disc o Tech article. On a Cbody they are rear mounted.
If that is what you've done, just swap the spindles side to side so the calipers are on the rear and you'll be good to go. You MIGHT have to tweak the bracket where the flex line connects to the hard line to correct the angle to the caliper but that's it.
Those 14" ones should work. I used the Russell stainless braided DOT certified ones and I think they were 13". I just had to rotate the frame bracket and line slightly to take the sharp hose angle out of it.