My old MSD 6AL manual states, not to use Iridium plugs so it all depends on what ignition system you use.
I run standard copper core NGK plugs on all my vehicles which are pretty forgiving. In a worst case I just burn them clean with a blow torch.
Most of my performance vehicles are ignited by MSD 6 series which supplies enough spark to ignite the fuel at any RPM range if its single dual triple or quad carburetted.