James the buss wire is uninsulated tin or silver coated solid copper, no reason to use an insulated wire in this application.
Since you had the top plates coated on both sides you will need to remove the powder coating on the underside where the terminal strips are attached to the top plate. A metal to metal contact is always required when grounding a part or component, and using star washers helps to cut into the plate for better contact. A grounding wire to all terminal strips connected to the grounding lug (paint removed from top plate) would accomplish the same results. This might or might not pick up some hum.
Hope this answers your questions.