Measuring the port...
By the way, if you don't have a numbered drill set to use for measurement, you can use a couple other methods...
Mark the tip of an awl with a dark colored marker, insert the tip into the port, give it a twist and measure at the shinny ring where the awl contacted the side of the port.
Or, you can also use a piece of solder. Slightly flatten a piece of solder about 1/4 of an inch away from the end (so it resembles a garden hose with a bulge in it) and push it into the port until the slight bulge contacts the edge of the port. It should leave an impression on the solder which you can measure with a caliper.
Thanks again