On a real HEI, just ground the "tach" terminal, the one right beside the main power wire that goes to the distributor cap.
Jerry
I had that issue on my HEI tach wire. I had the bright idea to use a short pigtail to that terminal on the cap for ease of attaching a tach for tuneups.
Problem is, if the end of the dangling pigtail gets too close to ground, it will arc across and cause a poor running condition which will cause one to pull one's ear hair out trying to find out what's going on. It was during that adventure that I learned of how folks use that terminal as a kill switch.
Carl
