By the way: Is there some consistent difference between lasts designated with three digits and lasts with two?
One needs a higher doctorate in EG lastology to anwer that question. I haven't come that far, but I'm working on it.
I don't think that there's that much system to the last numbers. Most of the current-generation lasts are 3 digits (808, 888, 202, 606), while most of the two-digit lasts are previous-generation (32, 33, 88, 61, 64). Of course, 89 and 82 are exceptions to the rule.