Milling the Heads How much?

The best thing to do is to blueprint everything. Don't take the specifications at face value. MEASURE them. All of the specs given on parts I have always considered as a "guide" if you will. Because of variancies in machining process and the mere temperature of the air, when you get down to measuring CC's and thousandths of an inch, almost anything can make a difference. I would invest in a good CC kit with a nice burette and the whole shoot and match. They aren't expensive and they are literally worth their weight in gold when it comes to seperating the bullshit of bench racing from reality. You will see for yourself exactly how many CC's will make "X" amount of difference and what it takes to get there.