It actually predates System 7 Pro, Apple charged for 7.1 upgrade disks. 7.0.1 was the very last "free" version, which works out pretty well, since it was also the very last "full" system that was omnicompatible with all current macs that existed as of its creation (I don't consider the 7.5 NAD to count since its not a full system file, it has limitations). Don't forget to run System Tune-Up 1.1.1 for 7.0.1.
So, you can go up to 7.0.1, then skip up to 7.5.3, and I'm not too sure after that, since I never stray beyond 7.1.2
And, after posting, I can see Charlieman Ninja'd me to the explanation for System 7.1
For System 7.1.2, don't forget to run System Update 3.
