The chart you sent me has 141 cfm @ .600" lift and 25" water pressure, gives a potential hp of 153 hp. The head I have gives 155 cfm @0.550" lift and 25"water pressure. Im told the differnce comes from the pot casting being higher in the head.

The interesting thing about the chart you snet me is that the exhaust is flowing 93% of the inlets at 0.600" lift.

Most A series heads including mine struggle to get to 70% of the inlet flow, especially if you have large valves.

Some literature I have seen on port development seems to say design for 70% Ex/In flow, in non cross flow engines with one port per cylinder. But whatever works for your setup is what its all about.