Your best shot is to take a panel from a bike that is either original or the color you want to match to your PPG paint jobber with a Prophet spectrophotometer. PPG will not have any information on the original colors. A side panel is the best option here. Keep in mind that 34 years of sun exposure will have faded the red, so a perfect match will be in your mind only. Normally I would suggest using the inside, but with the candies and metallics I have noticed that the inside does not have the same base.
Translucent colors (candies) tend to fade more rapidly and since the color depends largely on the basecoate (gold, silver, even white) it will take more than just a color match to reproduce the original finish.
I'd talk to your painter and maybe select a color you like and have him try it over silver and gold basecoats to choose what most closely appeals to your mind's eye. The painter has as much to do with the color as the paint mixer with these paints.
I've worked as a paint chemist for PPG for 30 years so make what you want of my suggestion.