K-Frame modifications - making a DC K-Frame

Yup you read right. @Jim Lusk is the man. I tagged him so maybe he'll chime in.
I'm hoping that he does chime in. I read on a very old thread, maybe from 2010, that he had a PDF of the instructions. I've seen the video, and maybe I need to go back and watch it again. He indicates how much aft setback is required, but I'm not sure I saw how far down to make the cuts. I'm pretty sure that my fab skills are up to the task, just want to make sure I don't screw it up. Spool mount k-frames just aren't as easy to find as they used to be.