Jim,
I worked in a carburetor repair shop for about 10 years. We had reamers that we used to open up the sizes in jets.
If you use a drill the swirl from the flutes and cutting will affect the fuel flow.
We tested everything on "wet-flow" benches.
For gauging there were several sets of round plug gauges. Starrett I believe????
Some people couldn't figure out how a jet ( say .055 size could be drilled out to .063, and flow less fuel).
On Holley jets, there is a funnel shaped chamfer on the entry side of the jet. This is critical of the flow.
Also, I have seen guys store their extra jets on a piece of mig welding wire.
After they rumble around in the toolbox for a month or so, the mig wire eats small imperfections into the bore of the brass jets.
The jets don't flow like they were supposed to anymore.
I have measured new jets from Holley before and find the same # jet with 3 different sizes.
After around #55 or so, the hole size is not the jet number size.
A #60 jet may measure .060, but a #78 jet may measure .090.
Try using reamers for opening up the flow and deburr the holes the best you can.
Hope this helps,
JAckal