Spark Plug Help

I have always used Autolite's they are cheap and out last Champions


If the plugs are fouled than it's too rich, carb, choke problem ?
I sent the carb off to get rebuilt professionally; I understand there could still be a problem with it if it wasn’t done correctly and The choke seems to be fully operational opening and closing when it needs to. Mechanic suggested I start by replacing spark plugs and go from there. Sound like a decent way to start or y’all recommend somethin else?