I was able to get aircraft bits (partial flute, long reach) at my local hardware store. They only carried 1/4 and 5/16" They required a lot of "pecking" to keep the chips from clogging the flutes.
Cleveland twist drill carries the 9/32' that McCandless suggested in the MP engine book and they have fully fluted bits.Even with the full flute don't try to get it all in one stroke.
https://www.cutting-tool-supply.com/ClevelandTwistDrill/
Be sure to use the correct speed, it's a pretty splindly bit. The calculations work out at approx 1000 rpm.

It may be ugly, but it sure is slow.

Girls comb their hair in rear view mirrors and the boys try to look so hard....