What are you trying to identify them as?
2V or 4V?...
4V have much better exhaust ports and should have the number "4" stamped on the front/top of the heads which is visible with valve covers still on.
2V have small exhaust ports but allow alot more airspeed which helps with daily driving.
4V are for racing applications mostly, but (like I had) can be used as a daily driver also, but more costly in fuel. Gotta love the power tho when the DP opens up!..
Nothing beats the sound of a V8