what exactly do you mean by measure? valve size? comb chamber size?
if they are stock heads, you'll see date codes cast into the springed side of the head (under the valve cover), and more than likely a couple Ford emblems cast into them as well...
the actual casting number (i.e. E7TE, E6SE, etc.) will be cast into the underside of the intake runner-you have to take the intake off to see it-with a mirror if the heads are still bolted down.
if they're off the engine, look on the mating side of the head under the intake runner and you should be able to see what casting number they are
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...