We construct redness-greenness (r,g) coordinates to fit the spectral locus into a triangle in the normalised CIE 2006 LMS plane. The reflection spectra for the Munsell patches for blackbody illuminants from 5000 to 6500 K appear as near circles in this space, suggesting that equal steps in (r,g) space may correspond to equal perceived colour contrasts within the gamut of reflective colours. We fit a matrix to convert from XYZ to LMS for reflective colours.
Richard A. Kirk, "Chromaticity coordinates for graphic arts based on CIE 2006 LMS with even spacing of Munsell colours" in Proc. IS&T 27th Color and Imaging Conf., 2019, pp 215 - 219, https://doi.org/10.2352/issn.2169-2629.2019.27.38