Play the 'Match the faded fiberglass game'....
..for which there seems no winner.
What lurks under decal stripes and top of metal surfaces is pretty much what we could all call White - very likely what the fiberglass body panels looked like years ago. The painted metal bits simply chalk and their fasteners rust with age, but a little soda blasting and change of screws take care of the rust - not their color.
But, since it would be near impossible to resuscitate the original white gel coat or fiberglass finish, it would be a lot easier to shoot the metal bits like the bottom rail, door frame, and other pieces that overlay the body ..to match the body panels.
Finding a color match is another thing. It seemed easy to go to Lowes/Home Depot and buy some off-white. You can see the two 'creams' I got are too yellow. I tried different primer to no effect. When next to these Creams the old body has a green cast.
In an Ah-Ha! moment, I pulled out a Pantone printing ink color guide. Not thinking that folks don't much print white ink, or shades thereof...?
I got pretty close with some off-white envelopes. My next trip will be to the auto paint store where they have all the colors. There's a place, automotivetouchup.com, that can make you commercial quality, 12oz spray of any known auto color.
I had them make me a can of a fancy Mercedes gray ...as all the different material parts below the beltline have also faded to different colors. It's cheaper to test with an aerosol before you commit to a big job.
If you've found a system that works, please share.