"... and door lock key numbers.... to get a closer data point?"
A curve ball for Brad's list: Early '57 T1 A; lock # is 5462, original locks per the original owner (square handles). Maybe they just pulled them out of a box at random when fitting them to the handles? Bottom of the barrel? The car was built with a mix of other "leftovers" and contemporary parts; early mirror but padded sunvisors etc.
Dennis, If you have an early 57 T1 with lock number 5462 that would absolutely fit into Brads table you did not mention what your chassis number is? The German car codes book that I have for early Porsche locks indicate that there were several series of codes used in this time frame and I have observed a few series that were not listed as being for Porsche. There are many possible explanations for this several German cars of the era are listed as using the same key blanks and having overlapping code numbering. It is very possible that some of these other cars may have also used the same key cylinder and were replaced at some time. I show the following sequences for lock code numbering: 926-975, 1201-1266, 5406-5552, 7500-7569,5350-5430, 5436-5494, 64111-64130. Notice that these are not in sequential order there are several other possible numbering series listed in the code book. If your car was built before May or June of 57 then your 5462 code certainly falls within the expected sequences. Also notice that 5462 falls within two different sequences of lock codes. These are four gate locks and there are only so many variations possible some of them are duplicated ...many of them are duplicated some of the codes lead to the same key cuts so even with different codes the keys could be the same. How many possibilities are there for four different gates? ...or maybe we really shouldn't ask this question?
