Heads are bad on my old 239. Block is good. I can rebuild the 239 heads; however, I have a set of 312 heads with matching 4bbl intake that will bolt on without the usual intake port matching problems. Question: will the 312 heads (identified by serial number) fit the 239ci engine? I acknowledge that the matchup w might be "putting lipstick on a pig"; however, I am in a time crunch and the question remains: Will the 312 heads work on the 239 ? Thanks!