With the help of George Goff, I was able to finish up the firewall penetrations
Mixed up a batch of ProSeal to seal the stainless steel firewall penetration fittings to the firewall. Applied the ProSeal to the stainless steel RV-14 penetration fittings purchased from Van's. Inserted the 3 fittinsg into the 1" holes previously drilled (one on each side and one in the middle of the firewall), and drove 2 AN470AD4-4 rivets per fitting with George holding the bucking bar on the cabin side of the firewall.
Tightened the 2 screws/nuts securing the ANL Current Limiter fuse holder to the firewall.