Location of Cowl Split on Firewall

[macrafic]

Hey, all you 7A builders out there. I'm fitting my mounting strips for my camlocs and don't have my cowl yet. I want to make sure that my strips are of the length/position to allow me to appropriately locate camlocs along the firewall relative to the upper and lower cowl halves.

So, my question is, how can I tell where my upper/lower cowl split occurs on my firewall? Does an extended line splitting the NACA vent and perpendicular to the firewall identify this for me (that's the best I can tell from looking at RV pictures)? Is there a more precise way of identifying this point?

As always