[ChrisMAg2]

Richard,
unfortunaly the whole topic is far more difficult then what you outlined above.
I attached the listing and designation of Michael Ullmann's Luftwaffe colors book (1997, english edition by Hikoki) to show in how far your thought on the different varieties (of RLM 81) are valid. As i.e. reg RLM 76 ("Lichtblau/ light blue")- other sources (i.e. Monogram painting guide) claim there more then just two varieties for this shade: upto 4.

Then, FYI, you cannot go for the names of the colors, because in the original RLM designation there were none, there were only the numbers. The names are postwar additions to help describing the different colors. And the names are nowhere standardised.

Finaly, matching the original paint and a printed color chip is not a workable possiblility, because a printed paint and the original sample you want matched are not of the same "paint-typ and -compostion". And since the matching will most probabely not be in a controlled, callibrated enviroment, the results could end up being very questionable.
Also: pls. keep in mind that a paint might have changed over time -atleast on the very surface. So you have to make sure the paint was/ is not covered with added clear coatings or waxes, because this will for sure change the color appearance. To have (a) sure and valid sample(-s) to match, you cannot avoid taking (a) sample(-s) and analysing the cut-through(-s) with a microscope. These samples can also be used to analyse the compostion of the pigments (i.e. with an electron-microscope). A photographic/ visual matching alone is -IMO- not sufficient to backup/ decline a complex matter like this.