Please tell me about 80-84 318 cop car engines.

Made a new Mopar friend today with a 65 Dart. He has what he was told was a cop motor, casting # 4104230 with 587 heads on it. Are the heads correct? What pistons would be in it? Compression ratio? Want to get him signed up, clued in, and help him out. Any info is much appreciated, the history on his engine is fuzzy, and it runs good so he's not gonna tear it down to find out, but is naturally curious.