Aluminum slant build

New to the forum, first post, Don't yell at me! I read Dan's coments on the correct head for the aluminum slant six. I have some older heads, one with Star on the upper rail and it has smaller chambers than my 2843169 castings. My question is wouldn't the smaller chamber head be better for the aluminum block upper support? I would like to hear from anyone with early haed numbers, I have some 212 and 220 numbers in my stuff. Thanks for any input.