Depends on how ham-handed you are. If you have large hands, then you need more space. Looking proto is nice, but you can't escape the fact that your hand isn't proto at all.
You have a 50' boxcar that has the front truck totally derailed. There are 5 cars in front of it, and 4 cars behind it. On each side, there are 89' autoracks. Can you rerail that front truck with 1 3/4" spacing? If you can do that without doing the Godzilla thing, then go for it. If you can't, then forget about the proto looks. You're fooling yourself if you say it'll never derail there.
Kennedy