hi,
maybe I'm a bit off, but I take it that the car is yours, and you have possession of it, as you haven't found any color code stickers on the car...
Then, my suggestion is to bring the car to your painter or paint supply store and have them mix your "touch-up" color based on what you actually have on there!
Even if the color is indeed the L87 code, it surely has lost some of its "original flavour" over the years and doing "touch-up" paint on small areas are always a bit tricky.
Mix up some L87 hue and do a sample bit on a piece of metal and put it against your car. That would give some indications.
Some paint-shops / professional painters also has some kind of "gadget" to "shoot" the actual color of your car to get the "recipe" to mix the paint to the correct hue.
My dad-in-law did some touch-up paint repairs to an old -36 Rolls-Royce, which had been repainted through the years and naturally the codes was long gone. After a few attempts from the local painter, the painter managed to mix a colour to a perfect match to what was already on there.
Good luck!
BR,