Best method for drilling 5 evenly spaced holes. In a circle.

[astroracer]

Make yourself a jig.
Use a flat piece of 2 x 6 or a piece of aluminum plate and make an arbor that fits the center I.D. of your adapter with very little slop. Screw this to the 2 x 6.
Set the jig up in your mill, zero the center and then drill two holes spaced for your bolt pattern. Spend some time making sure the radius and 72* angle is deadnuts between the two holes. The easiest way to do this is to use a rotor. Set up the center arbor and use the rotor as a pattern.
You can now set one of your adapters in your jig and drill the first lug hole. (Don't move the jig or you'll have to re-zero the holes to your cutter.) When this is done rotate the adapter 72* and pin it through the "extra" hole in your jig. This establishes the 72* angle so it had better be right. Drill the next hole, spin the adapter again, pinning it through this new hole to the jig.
You can drill all five holes this way and if your jig is right the adapter will be right.
Have fun
Mark