Some interesting info from another collector on what's rare in the Snake world.
Serpentine set is the rarest "set" to my knowledge at 50 sets. In order of rarity my research has come up with the than Carol Wilkerson 3" SS and 3" nickel (20 or less of each). There are 26 nickel cali combats made. In terms of roll marks, 100 cased sets of boas (1200 boas in total though), 200 stalkers, 200 call combats in blue, 226 nickel python targets... (251-26 that became nickel cali combats =226 remaining), 250 silver Snake, 250 python 10 pointers, and 250 python silhouettes. 1000 grizzlies, combat cobras, Snake eyes (500 in each finish). 2000 Kodiak. There are some rarer birds out there, but not unique roll mark.... 5" anaconda..... Heck even the 3" pythons aren't unique in terms of roll mark.
Of course don't forget single digit S/N Pythons, those would cause a big headache to the CFO for registration, believe me. When I had my 1957 Python re-registered, their system showed 27 other Colts with that serial number, so I had to educate them on the Python history and they approved it on the spot.