I have run my Autolite 46 spark plugs with an early Petronix with the flame thrower coil for about 30,000 miles. The stock 292 is now stumbling a bit with foot on brake at a stop . I figure I'll change the plugs for a start, and then rebuild the later holley 4 barrel if needed. I figure I'll buy another set of Autolite 46 plugs unless someone can strongly recommend a better plug for use with the Petronix. Also, should I gap the plugs wider than stock specs.  The motor is a stock 1960 292 with the truck type heads with the smaller valves. High performance is not the goal. I like a smooth running engine with best possible gas mileage.