71scampy- there was no reason to tell Rumblefish he doesn't know what he's talking about....he's a MODERATOR here, and obviously very knowledgable about Small Block Mopars....a little bit of time on the forum would more than prove that to you.
I have dealt with alot of 302' casting heads, and they all have the casting number on them....if you can't post up pictures to substantiate your claim that the only numbers on the heads are 714 - and 10...then you need to just wait till you can...cause you may have some replacement heads off a 273 or something.
ALL roller engines are black, what color are your wonder heads? if they are ANY COLOR BUT BLACK they aren't 302's.
It takes extensive modifications to make a 302' head flow 275 cfm...so get ready to sink some dough into whatever they are....I know....I had a 88' Roller 318, STD. bore, STD Stroke dyno'd LONG BEFORE HotRod did it, and it made over 400hp/420 ft lbs. of torque.
I used Stainless 1.88/1.60 valves and .550" dual springs with dampners, and there was nearly $250 in just machine work BEFORE I home ported them.
Good luck, none the less.