The modified B & C ground block on the forward side of the firewall.
The modified B & C ground block on the aft side of the firewall.
This modification should work out quite well to establish a good solid airframe ground. The ground lead from the battery and the starter will connect directly onto the 5/16" brass stud and the spade leads will be available as grounding points for sensors, etc. The only down side is that both the starter and battery ground cables will need to be made longer to get to the grounding stud on the firewall. Where is that cable stretcher when you need it?