Yep. I started looking for the SVO and LSC spare early on, but they are rare as hens' teeth. I think they have a bit more offset than the Town Car spare.

The TC / Panther spare is going to be the easiest to find with the best offset. Pretty much guaranteed to be able to find one in any salvage yard.

I actually did a much more in-depth write-up of what wheels might work and what ones won't. I edited it down quite a bit for posting in the forums.