Guess my 273 hp

I had the old stock SW tach in my 65 "S" and it would register up to 6K, I would bounce that needle very easily with the stock 500 CFM carb and manifolds. I dont think it was very accurate either, needle seemed heavy, slow to respond. I think it was more for looks myself positioned down by your left knee........And ditch that 6K orange box ECU. Borrow an MSD, Crane or Mallory and see if it helps.