Agreed, a 340 is only 7% bigger than a 318 basically has to turnabout 7% higher for same hp.
6050 rpm 340 = 6500 rpm 318. A 60 thou over 318/328 ain't too far off a 340 especially in the 350-450 hp range and even better if they can take a 4 inch bore for a 333. The only real problem with the 318 is dodge also made abundant of 360's too. But still doesn't stop the 318's from being a very capable engines, ford makes 3 different 351's but doesn't stop 289/302 being one of there most popular engines built, even when stroked is only 331/347. Or LS guy's doing NA 450+ hp 4.8-5.3L engines.
