You can purchase 60% gloss, etc at your local supplier. Bill Hirsch, Eastwood also carry various shades of the correct black.
Years ago you use to have to add a deading agent which made it difficult to spray additional parts that you may have missed. Sometimes the shade wouldn’t be exact. If your going to the effort to do a correct restoration, do the research on the shade of black and do it correctly, it doesn’t take any more time to do it right. Good luck.
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Ron Green
AACA Member #337715
AACA Gettysburg Region (board member)
President Amphicar Club (IAOC)