I have a more similar set-up. The lift on my cam is .630 and I'm real close to coil bind, so you must be past that point. Stud girdle, like 73RS said, is about 1/8th of an inch down on the adjusting nut. I'm sure if your valves were hitting the top of the pistons you would know it by now. You'd have a few bent valves that would be staying open, so it's time to look real close at the springs.