Cams for 318's

Ok I did some quick looking into it it looks like the hi compression 273 had dome pistons. nice ! I didn't know. The low comp 273 had the 4 valve releifs i don't think I've ever seen a high comp 273 how many were produced anyone know? I do think I am correct on the 273 closed chamber head though which gets installed on 318s alot to bump CR.
( Sorry, I fibbed about never mentioning 273 again...LOL! :))