My thought would be using the TS-40 Black Mt. wouldn't need and might not even show a silver base coat. As always picnic spoons are your friend. Suggestion, try a light coat of Model Master #2983 Multi color glitter clear spray or MM #2984 Silver glitter. These are both enamels, but over the Tamiya paint I don't think there would be an issue. Again, the spoon thing. This will help you see if the MM sprays are even needed to get the finish you're looking for. Many OEM Black Mt. colors in the past have a very slight multicolored flake effect as my '05 GTO did. This was not noticeable unless you were standing right next to the car.