I just returned from the Challenger lair out back of my house, where I removed the stud in the '71 and re-installed it in the forward hole in the bracket on my trunk floor. When I bought this car last year, my trunk was nekid except for a cheap repro trunk mat, and I bought a spare tire stud from YO based on info a friend with a '71 Challenger vert he's owned since the early '70's gave me. IIRC YO had 3 sizes and the one they had that was approximately 8" OAL was the one closest to what was on his car.
At any rate, I reinstalled the stud in the forward location, put my space saver, base, and cannister bracket back in, and lo and behold, I find the hook now can be installed on the stud.
I have an incorrect base and still don't know if the base should be black or dove gray for a 10/70 SBD car, so the quest continues.
But in the meantime, my tire is now properly located and I know a little more that I didn't know before. Thanks Earl and Pete once again for sharing your knowledge!