Well, I can't be 100% sure of what exact color you're looking for, but I'm guessing the amber/green mix will get you what you want. Have you considered just using a triple amber? They are pretty nice. It's kind of a deep yellow but I like it quite a bit.

You can ignore the one on the bottom, it's a quad CREE XB-D A/A/A/A. The top one is a tri CREE XP-E2 A/A/A. I originally took this photo to show how much better the tri XP-E2 is.
CREE Amber.jpg