Bob G is correct. The Assembly Manual shows all 4 pieces of Hardware as having an S36 Finish - Zinc Plate and Dichromate.
I have attached details of the 4 pieces of Hardware from the Ford Standard and Utility Parts Catalog (except for the 34942 External Lock Washer which did not appear in any S&UPC from 1961 through 1975, but shows up in AMK's Guide to Ford Fasteners). Note that as the S&UPC's are Service Parts, all appear with either a Zinc, or Cad Finish. However, to be "Concourse (Assembly Line) Correct", all should be the Zinc-Dichromate Finish as previously noted.
Also of interest to those inquiring minds, yes, the 390's are shown to use the same attaching Hardware. The 6 Cylinder Engine used the most inboard Starter Motor Bolt on the "engine side", and on the "firewall (dash) side", the Assembly Manual does not detail what was used. However, I would guess that it's a "pretty good bet" that the same Hardware was used to attach the cable to the firewall as the V8's did.
Hope this helps.
Bob