I kinda hope you leave the clay out of this test. Common sense says if you see a ridge near the valve job in the chamber throw a old valve in the head to protect the valve job and address it. I personally only sink the valve enough to give me room for a 15 degree top cut. Your last two moves if we go far enough will get you to our target. We know the bolt bulge has to be minimized and we know the short side had to be lowered and shaped. But every step we take we are going to lose the do it yourself crowd. Like I think it was Brian said an intake manifold is going to slow the airspeed some. When I first did the set of heads I run now back in 2008 I needed my quickly ported super Victor to calm the head down enough to hit 318 cfm with a 2.08 valve. I have since learned how to slow the airspeed down enough without using the intake as a crutch. And between being able to now set the throat dimension on my seat machine and giving the heads a better competition valve job I’ve picked up 16 more cfm on my next set of heads. Heck the ones on the car now had my old 4 angle valve job that I did with Neway cutters. And I know the throat is under 88%