I personally would just run the factory plugs

For aftermarket heads with a flat seat I use NGK FR5 or on blown or high compression motors I use NGK BKR6EY (since there is no FR6). On stock tapered seat heads I use NGK TR5 or TR6 for the blower cars like my Terminator. Personally I think you are way better off to use standard plugs and replace them fairly often than to use exotic materials plugs like Platinum or Iridium and with high boost blown applications the tiny electrodes on these exotic plugs can actually promote spark blow out.

-Matthew

^^^great info Matt, thanks