The run on problem is the alternator supplying current to the ignition[msd] module.This is a common problem the tech guys see at the drags every weekend.They will turn off the main power cut off switch while the engine is running for safety reasons at the track,if it keeps running you don't pass tech. The cure is to wire the main output lead from the alternator though the ignition switch or wire a relay into the alt ckt as you would a fan relay.
Perry.
