Did he say open chamber heads ?? I did not see which heads he said other then iron heads. That said I use 906 open chamber iron heads in the 440 in my 63. And I use the KB quench pad pistons. I had to work the pistons and chambers to get all my chambers in the .040 to .045 quench area and I got it to come out at 10.0 comp. I can run 38 total timing all in by 2000 rpm and I run 92 and 93 pump with no ping. I use the MP .557 cam with 296 advertised duration and it works nice with my combo. Ron