My Brother In Law is putting together a 56 chevy truck with a 355 C I small block. It is running 7 to 1 compression and a B&M 162 blower with the super street B&M cam. it has a holley 750 cfm carb and MSD ignition. it has the 5/8 inch plugs but I don't think the heat range is correct. Anybody run something similar and do you have ideas on what spark plugs should work with this combo? Any educated guesses would be greatly appreciated.