440 tunnel ram

With the MSD ignition, you should be running a projected tip spark plug in the proper temperature range. I would start with a champion RC12YC4 to start with, they come set with .040 gaps. Before I suggest wide gaps, though, what coil are you running? With good quality plug wires and an MSD Blaster II or III, you should be able to open the gap to .045 without any problems. I meant to ask what exhaust your running as well. I am making suggestions based on the presumption of open headers, what with it being a race car and all.