Dave,
My motor and transmission isn't original, and I have the exact same problem with the linkage. The powerglide linkage runs right across where the numbers are. When we had it up on the rack last Feb., I asked my favorite mechanic about looking under the linkage for the numbers. He said, "Are you really sure you want to do that?!?" And gave me a look that would cut steel. I don't suppose the fact that we had worked for two hours setting the passing gear, etc. had much to do with it.
If you are brave enough to pull it off for a look, let me know how it goes!
BTW, headed for my favorite show, swap, etc. in September. Wish me luck!
Phillip