cylinder head I.D. mind games!!

I've been aving a bit of trouble with something very simple! I'm building a '69 396 and it's time to order pistons...in which I can't do untill i get a solid answer on just I've got as far as cylinder head cc's.the heads i've got are casting number 3933148,in which the first source i checked out said were 112 cc open chamber heads. But the second source i just so happened to gaze upon stated that they are ,indeed,109.4 cc heads.well,I thought I'de get a 3rd opinion only to have 122 cc's thrown at me to add to the jumble!!I've checked time and again for answers ,but end up with the same findings.Some help from a wise soul would MUCH be appreciated...please help!!