After entirely too much research (including staring at a lot of photos in this thread for a combined total of several hours) I picked up my 1958 this week and immediately put on the 275/70R18 KO3s that my dealer was kind enough to price match Tire Rack on.
The Les Schwab I visited for install didn't want to mount the spare claiming it wouldn't fit. The indie shop I visited the next morning said the same, but I talked them into doing it anyway. It just barely made it in, and it feels like it's maybe a half inch too big to fit in cleanly because it's catching on the two stays in the front keeping the tire from making contact with the panhard rod and it's touching the rear frame rail. I still need to do some adjusting, and maybe I'll just have to store it aired down a little, but wanted to share my experience since it wasn't smooth sailing. Worth it though!
View attachment 5494
View attachment 5495
View attachment 5496