It has been so long ago since I run a stock 440 that I can't remember if it was a .040 or .055 over engine,but I put them on with no problems on a new build.I would like to tell you that them being 440-1 heads they were made to bolt on a stock bore 440 but I have never done it so I won't,but you can call Indy and they will tell you.They have always tried to be helpful and the one time they could not answer my question they told me they would have Russ call me and believe it or not he did.