The stock head bolts are a torque-to-yield design, and can't be re-used. If you purchase new GM bolts, the procedure is to tighten them to 45 Ft/Lb, then continue turning another 90deg, or to 60 Ft/Lb, whichever comes first.
ARPs, on the other hand, usually get torqued to somewhere between 75-85 Ft/Lb, depending on your setup. If you haven't had the cylinders honed with a torque plate, you'd want to stay on the lower side of that.
