I'm in the process of attempting to perform some cleanup in this panel and also reconfiguring and adding several new circuits. This panel is a vintage Westinghouse/Bryant Electric 100 amp main service panel of unknown date, Catalog No. B20-20 FN, SN, with 20 circuit capacity. Again, I'm performing cleanup, but as you'll note, the neutrals and grounds are all grouped together on the right side of the panel are are pretty well maxed out, with no room to add neutrals and/or grounds.
That stated, my question pertains to adding an additional ground bar in this vintage panel. There are 3 sets of predrilled holes in the upper left section of the panel, but I can't locate a new ground bar with hole spacing that will line up with these existing holes. Therefore, I'm wondering if I can simply drill and tap two new holes in the bottom section of the case and install a new Eaton ground bar in that location, and then connect the new ground bar to the existing bar with #4 AWG ground wire?