Production numbers

Yes/No. 318s were ALWAYS low compression, they dropped them a couple decimal points in 1973. But you're being a 72, there's no difference between a 71 and a 72 318. or any 1967-1972 318 for that matter.

"All horsepower ratings before 1970 are gross measurements (without accessories and such). Ratings after model year 1971 are net measurements and are lower even for the identical engine from the years before." *Allpar

"The 318 LA, released in 1967, featured a 3.91 inch bore and a 3.312 stroke. Compression was a respectable 9.2:1 but would later be dropped from 9.2:1 to 8.6:1 for the 1973 model year to meet tightening emissions standards. Due to a change from gross to net horsepower ratings, horsepower would drop from 230 hp gross in 1967 to 150 hp net in 1971 despite the 318 otherwise not changing. The 318 would remain unchanged from 1973 to 1977, when further tightening emissions would result in a slight horsepower drop from 150 hp net to 145 hp net." *Book, Small Block Mopar Engines.
Ok, fair enough, I guess it still depends on who you ask, my info about the piston change for the 72 model year came from Valiant .org. thanks for your input, I guess all Mopar guys like to think their car is special