Remember, these cars were essentially hand built meaning there are variations.
1) I had, until I covered them in paint, the original scuff marks from rubbing 205/70's on the inner fender wells. Wasn't all the time of course, but it was there nonetheless. No additional scuffing since the 185's were installed.
2) The 205/70 spare wouldn't fit on the trunk mount stanchion, period--at least not with air in it! My "correct" [and inflated]185 just barely fits now, and from that fit it is easy to see how and why the 205 didn't.
My experience isn't true for everyone as Longtooth points out, but I won't believe it is unique, either.