Can someone please provide guidance on the correct finish and material for the underside of 1975 U.S. market 308GT4 engine cover and other horizontal panels? I believe it should be a matte black finish, material is a German spray-on product, but I have no confirmation. I’ve checked various resources such as Bluemel’s book and some unofficial pictures but would like to hear from actual owners and experts. Any information and pictures would be appreciated. Thank you. Jack.