HI tmritter44,
Very nice!
I usually find a way to make at least one mistake laying out the firewall. On the Onex, I decided to test the layout on some Home Depot lexan, and install it on the plane, so I could ensure I didn't interfere with any of the structure on the cockpit side. Then I used the lexan as a template to transfer the hole pattern onto the actual firewall.
Good Luck,
Wes