Have you looked at the choke? Has it started since you put the Ignitor on? Have you double checked the Ignitor wires, distributor cap and plug wires are on correctly?
any chance you got water in the gas tank? kid put the garden hose in there? Stranger thing happen. If it starts when you prime it and you can see the gas going into the carb I would think somethings wrong with the gas.
Used Cars for sale - Ford Mustang classifieds