My last of the red/grey Ford 861s has stopped running, suddenly and completely. It had been starting and running fine. Brush hogged two hours one day, started right up the next morning but died after about 5 seconds. No missing, rough run prelude; just quit as if the ignition had been turned off. Air intake is clean and the oil cup is at the correct level; 60% fuel in the tank; vapor valve open (excessive flow not tripped); fuel flow to carb verified (new Impco LP components in 2016). I had replaced all the plugs, wires, distributor cap and rotor, points condenser and coil in 2016, but found corrosion on the coil wire ends and the spark seemed weak, so...I replaced the wires, coil, points and condenser, plugs and, distributor cap and rotor (dust clover too) in that order with no improvement. Still weak and intermittent spark, and no start, nor even an occasional hit. I am officially out of my self-taught amateur mechanic depth. Any help will be greatly appreciated.