I used to have a 1970 300 Horsepower L48. It was overhauled using a stock cam, intake, carb, crank stroke, and exhaust manifolds. The block was honed and had a standard bore, it put out 325 horsepower and 386 feet pounds of torque on an engine dyno. I don't know how much change there was between 67 & 68 when the L48 as rated at 295 H/P and 69 & 70 when it was rated at 300 H/P.