Welcome to CHR. Hope you enjoy a long stay here.

You'd go with the head volume that fits your static compression needs, right? If your engine is set up for 210's and you go to 195's you're going to bump your compression. As far as better flow, I would expect that AFR's improvements from the mid 90's to now (20 years?) is going to be pretty significant, meaning that if you flow bench an old 210 compared to a new one you're going to see significant differences, but the answer is not to decrease volume unless you're making other changes, too. Curious, why are you asking, and why wouldn't you want the newer head with better flow, if there is a choice?