If you ask me, you are digging way to much into the "proper" color area. Just test, pick the ones you feel fits best and apply them. Everybody sees the colors slightly differently. There is also color blindness in different levels. That is why if it is close to the original, it should be good enough. Besides in time the plane changed its colors due to aging.
European modelers probably remember Opel's red from the early 90s and the hundreds of variations it got in the first 10 years of its life.
With airplanes is the same.
Again - pick several tones, test them out, mix them if you have, then pick and apply.
By the way you were about to send me an email a month ago with some decals that you needed evaluated. I never got that bud.