See post #7
Nitrous is almost as hard on head gaskets as boost. I have been running N2O for the last several years. Approx 10-1 CR and 150-200 HP shot on a 170 CID slant. Stock OEM head gasket, and head bolts. I do put hardened washers under the bolts, and torque about 5-10 LBS over stock. Never blown a head gasket. Main thing is to get the head and deck surface flat, and the proper finish.