Ok, how bout a stock 68 340? All I did was put a 750 carb on it and advance the cam 4*. This should show that the program is probably pretty dang close. View attachment 1714998465
Car Craft did a 69 340 Dart stock resto car in '85.. Bob Lambeck did a dead stock parts , blueprinted 340 stock intake/exhaust manifolds it engine dynoed,315 horsepower,similar torque to your Desktop analysis,RRR....