Has anyone used this conversion kit?

Unless something mechanical broke in the engine, if you have spark and fuel it should fire. Does "plenty of spark" mean you used a clamp-on timing light on cyl 1 & verified it flashes at the correct crank angle, then verified all other plug wires give a flash? "Plenty of fuel" could be "too rich". Try clamping off the fuel supply and firing w/ starter fluid sprayed down the carb throat. Are you sure the Pertronix is phased correctly, i.e. rotor tip aligns w/ plug post when it sparks? Search for posts and view youtubes.