273 is better than a 318 ...I say that just based on the High compression, and as 318 guys always say when chatting about the 340 "the bore has nothing to do with it..."
The first 2 years of the 318 (before the 340 came out) had high compression as well. Had a few people argue with me but when I pulled my original '68 out of my Coronet I was shocked that the pistons were only 0.030 in the hole and the measurements put it at about 9.2:1. If you look at the factory manual for '68/'69 they claim 9.2:1 or so as well. After the 340 came out my theory is the purposefully dropped the compression to make a large difference between the 340 and 318 in the brochure.
