On the subject of parchment, I'll give you my recent experience.

The parchment has a rather yellowish appearance (I have the parchment pearl, which is a parchment base with pearl mix). I thought mine needed to be redone (turns out after removing the panels, it was upgraded in 1997 already by the previous owner). After ordering the correct vinyl paint, turns out that's how it's supposed to look! I polled the female riders in the family, and they didn't care for it either (neither the parchment, nor the pearl). They also thought it made it look like it needed cleaning and didn't care for the shininess of the pearl.

So after getting some swatches from TMI, I've decided to go with 1968 (midyear)/1969 Camaro White Ivory. It's a little more closer to an actual white. Still not a true white, but that's fine (tried the generic Duplicolor and that was too white). TMI and Legendary will let you custom order the correct design for your year with the color of your choice if you order directly through them.