When we were restoring my car with a 6U Deluxe Light Parchment interior back in 2013, we too had a somewhat difficult time getting all of the Light Parchment pieces (seat upholstery, deluxe seat backs, door panels, quarter trim panels, dash and door paint, windlace, kick panels, lower dash knee pad, A-pillar pads, sun visors, console, deluxe horn pad, and convertible boot cover) to match.
Some of the materials and paints were too white, while others were too yellow – but I don’t recall any of them being on the brownish side - are you sure you have Light Parchment and not Saddle?
Color matching on a computer screen is always tricky (you no doubt saw the “Blue/Black or White/Gold Dress” controversy in the news a few days ago), but in the first photo below, you will see a TMI 1967 deluxe Light Parchment door panel, two 1967 TMI Light Parchment seat bottoms, and in the center is a swatch of the 1967 Light Parchment seat upholstery that originally came with the car. The swatch was cut from a part of the seat that was covered by the deluxe seat back, so there wouldn't be any sun/UV damage to the material that would have caused it to yellow or fade. It was then gently cleaned with soap and water to give us a good example of what the seat color was originally…
I did learn that TMI has at least two or three different colors of Light Parchment as well. The deluxe door panel and the seat bottom on the left are in TMI’s basic 1967 Light Parchment color (I believe it is color code 3096). The 1967 seat bottom on the right is in another TMI Light Parchment color (color code 2613). While not a perfect match, the 3096 color seemed to be much closer to the original color than the 2613 color did…
The next two photos are of the finished car. I think we did a pretty good job of getting all of the Light Parchment pieces to match, except for the windlace – it’s still a little too dark, but it’s all that’s available right now…
Hope this helps!
Kevin