'67 Dodge pickup color "Desert Turquoise" mixed by a local paint supply for me back in about 1981, matched by color chip, is what I used on my '67 Newport 383 to paint a new oil pan I got for it. At the time, only Chrysler Blue was available in spray cans or from Mopar Perf, so the mix it was. Got a PreVal sprayer and had some enamel "thinner" from Home Depot. Used Berryman's B-12 to prep the new oil pan and that paint is still there, looking good. Of course, what was mixed was acrylic enamel (OEM-spec) rather than the more inexpensive "enamel" they used for engine items back then. Kind of a "DIY approach", but it worked well.
Back then, 40+ years ago, finding a good local option was the best deal we had for things as "repro" usually applied only to some Chevy and Ford items. So it was serendipity to find an OEM exterior paint color which matched the engine paint (dang close if not exactly!). By that time, too, 25 years of engine heat had dulled the orig paint a bit, so we tried to compensate for that a bit, too. Places like Bill Hirsch and Kanter were places we saw advertised in Hemmings Motor News and basically "not close enough" to deal with for us. And, in this day and age, that might still be the case for some in the hobby. In more current times, finding a local good paint supply that can mix "single stage" acrylic enamel might be a trick, too.
Just my experiences, no more, no less.
CBODY67