I think Mexican Sand (darker) or Almond (lighter) are going to be the closest blends. You can order samples on the Kohler website

Here is a link that might be useful: Color Chip Store

If the idea is to get the closest match on color, you're in a difficult spot. With a toilet, you could take the tank cover to showrooms and compare. There's no piece to take from a shower stall.

What I would do is search online for the plumbing supply places, kitchen and bath showcases and design galleries near you. Next, come up with a list of brands - Kohler, American Standard, Toto, Gerber, etc. and find out which of the places carry which brands. Go there and plead your case and ask to borrow the color chip samples, putting down a deposit for it if requested. Try to get all the samples for all the brands at home at the same time, then pick the closest match.

Kohler made parchment (color #40) from 1976 through 1989. It is no longer made.

You may be able to find old fixtures at an architectural salvage dealer. I see them from time to time.

If you buy an old toilet, your plumber may have to modify it to meet current federal law on flushing limits -- but many jurisdictions overlook the requirement for heritage toilets. Ask your local plumbing inspector.