I did it a little ass backward since I don't have the right tools. I found my centers and drilled a pilot hole. Then I set my calipers to the radius I wanted. Using the pilot hole as my center I scribed a very fine circle around the pilot hole. Then I used my dremel tool with a metal cuting disk to cut the hole out. I tried to leave a little of the scribe line visible as I did my cut. Always better to leave too much material than the take too much off. Easier to remove material/metal than to add.
I used a half round bastard file to finish the hole off.
I don't know how much a quality hole saw/drill attachment cost but it would make cuting those holes a
WHOLE lot easier!
I usually do things the hard way. Gives me more of that quality me time in the garage