Boy, I can relate. Here is my tale...
If you take yesterday's formula and have the paint store run it through their system you don't get the paint color you want. That's because today's green, blue, orange, etc is not the same color as it was 50 years ago. So when you take 500 grams of today's blue, 100 grams of today's white and add them up per the old paint mix gram totals the color you end up with is not the same.
When I asked the paint store to mix up my Lime Gold in PPG DCC and I sprayed it out I ended up with something quite awful.
I asked around in this and the SAAC forum and Tim Lea shared his paint mix for Lime Gold, but it was in the Lesonal brand by Sikkens and no one within two states of me uses this paint. We can't use this mix ratio as we can't assume any of the individual colors cross over to other paint lines.
Finally we took our paint store's color match camera and shot the passenger door latch area (and other areas) of a survivor car and had them mix up a test sample.
We sprayed this out and it matched one small sliver of original paint left on my dash. I have yet to return to the original car and match our spray outs to this car.
Hopefully you have some area of the car still in original paint. Like the underside of the trunk that you can remove and bring to them. Have them mix up a very small test tube size sample and do a spray out on a spray out card. PPG DCC can still be had in single stage in some areas if that is your preference. Have them mix this if this is how you intend to respray the car. Otherwise, have them do it in a base coat system, spray it and clear coat the spray out. Then see if the color matches.
