Re-did the template I had created to reduce the line widths, to allow better center-punching of the holes to be drilled. Made another metal practice piece and was pleased with the results.
Re-marked the panel with the locations of the comm and xpndr, measured thrice, and drilled the holes.
Next up: cut the big hole for the Enigma EFIS, the ELT remote switch and the relatively simple round holes for the breakers and toggle switches.