I have previously posted about RevitPythonShell a number of times. In this post Dima Chiriacov gives a real-world example on using the shell to change the case of text.
There are quite a number of free add-ins which can easily change case too, like this one or this one (which also allows merging of text).
Read how to use RevitPythonShell at:
DP stuff: Convert Revit Text to Upper Case
