Patrick Dykes, the guy who sells 235/262/GMC parts , said he has seen many 235/261 engines run on dynos .According to him, a typical 235 with 2 carbs, cam and more compression makes 150-160 actual HP.The best he ever saw on a 235 with a cast iron head was 200 hp on an all out racer.The stockers have 120 or so actual hp.