Did a little measuring with an electronic caliper. Not saying it's perfect, but it's just to give me an idea of how much the chamfer takes up.

Overall diameter - 3.90"
Height of chamfer - .085"
Diameter to inside edge of chamfer - 3.75

What I did is calculated the volume of the overall diameter and height of the chamfer, then calculated the volume of the diameter of the chamfer and the height of the chamfer. I subtracted the latter from the former and divided by 2 since it is at an angle. I came up with .08 cubic inches and converted that to 1.3 CC's.

My math or how I went about it could be completely off, feel free to correct me if you'd like. Also, the overall height from the top of the piston to the top of the first ring groove is .25", and the height from the top of the first ring groove to the bottom of the chamfer is .165". I subtracted those 2, that's how I got the height of the chamfer.

I imagine the only way to calculate the volume of the valve reliefs would be to fill them with a liquid of some sort, I don't really have anything accurate enough for that.