Those aren't valve pockets. That's the flash from the camera off the cylinders. I know this because you can see the small dimples in the piston top that face forward on every magnum engine. Magnums don't use valve relief pistons.
As for boost, myself and lots of folks have ran oem pistons to 10 lbs boost as long as the ring gaps are wide, like .030" wide, the fuel rich, and the timing low.
