Whats the best plugs for a SBC Carb motor??

I keep reading that NGK6R plugs are great for LT1 motors, can these be used in a carb'd 70 350 ??? I have been thinking of coming over to the juice after my a$$ was handed to me this weekend by a similar car that I have but he was spraying a 150 shot. I'm looking to run a 150-250 cheater system. I alreay have a 6AL box, MSD wires and long-tubes, was wondering about plugs and also, what is the best way to run the spray? A dual stage on my MSD, or just all off the line on a one shot blast?? Also I've heard mentioned a retarder box, how exactly does that work?? Is it plug and play friendly with the 6AL ???

Im not sure what you mean by a retarder box but if your thinking of a window switch or an ignition that allows you to retard the spark when you are spraying then i can follow you. MSD makes a window switch that you can integrate into your 6AL i do believe.