Factory 68-71 340 puts 325HP on GM Dyno

Well if you design the base engine (273, etc) to be bad-*** then it's easy to hot-rod it. Chrysler's motors were ALL good, not just the high-performance ones, which I think says a lot. Seems like GM had to spend a lot more time developing their performance engines because they had to change so much more than the Chryslers to make them fast.