I went by my LHS this afternoon to see whats new - and they said the MTH Southern Railway F-7s had come in. These are painted and lettered in the 1960s - 1970s era scheme with large letters and no nose herald. He pulled out a box to let me see them (sorry I didn't take any pictures) and they look very good. Even the horn is right with 4 forward trumpets and 1 rear trumpet. Some details may have to be added to make it truely Southern (like the walkway brackets) but overall it has the correct feel.
In this configuration, they would work for the 1959 - 1968 since they do not have spark arrestors on the stacks. I plan to get a set with Hi-rail wheels and may eventually fix the pilots. I know I can get the scale version, but I run traditional track and think the smaller flanges won't work through the switches.
Now, we need to convince MTH to run the Southern F-7 in the 1950s green paint so I can have these in both HO (Athearn Genesis) and O scale. I have mentioned this a few times through their website, so we shall see.
Get 'em while you can!