Jim,
1.I think it's going to be easier to measure bit angles on an optical comparator. For the internal angle of the adapter, can you cut the one you have apart? Do you own it? Then measure the angle of that one.

2. Not sure if you want the angle to match as the bit might get stuck. They might have to be slighly different.

3. Consider boring a through hole as well so that if a bit is stuck, you can take off the adapter and insert a pin and knock the bit out.

4. Where does that set screw hit? On the shank below the pyramid?

Brad