I think the best way to find out is to do a mock up using a pushrod length checker. I got a trick flow checker for 11 and change I think.
Put some grease on the tip of the valve, or use a sharpie to color it in(thats what I used). Tighten the rocker and then hand crank it a few times. Adjust the pushrod accordingly until you get a nice straight mark, right in the center of the valve tip.
Then just pull it out and measure it.