well, stock heads (E7TE) are 62cc's nominal for combustion chamber, with a 124cc intake runner, and about a 50cc exhaust port (I think)...
as far as unported cfm's for stock heads, they're terrible...probably somewhere in the neighborhood of 175-180 for intake side @ 0.500"...exhaust flow probably about 110 @ 0.500". ported flow #'s are improved, but still not great...if you're looking for good flowing stockers, ck out a set of thumper heads. Using the stock valves that are backcut, with a 5 angle valve job, they flow significantly better-and are enough to put your 'stang into the 12's with modest bolt on's...and they only cost $600.
lemme try to find the weblink, and i'll post it...