One more thought, See what that Demon is squirting.
It wouldn't be the first time if it turned out to be gas contaminated with Diesel fuel or water.One won't start on poor fuel.
If it were mine it would get a good squirt of starting fluid to see if it would respond.
Also check for strong spark at the plug by holding a wire to make it jump to the PLUG in the engine.A weak spark may jump an air gap outside the engine but be too weak to fire the plug under compression.
I am reading that this is an HEI type coil in cap distributor--it wasn't stated.
