Yes, it is OK.1/ If I can request something, I would prefer if your fork didn't "redefine" existing OXCE features. I didn't check your changes lately, but I remember from earlier that you have changed the behavior of the "isLeeroyJenkins" flag for example. If not "too much work", I would like to see new flags in such cases (to prevent documentation confusion/mismatch). If not, I'll survive.
2/ Lastly, in version.h:
#define OPENXCOM_VERSION_ENGINE "Extended"
#define OPENXCOM_VERSION_SHORT "Extended 7.8.8 + Brutal AI 3.5.3"
#define OPENXCOM_VERSION_LONG "7.8.8.0"
#define OPENXCOM_VERSION_NUMBER 7,8,8,0
One (or both) of the first two lines should always have something indicating that it is your fork.
This will make sure we know which version was used to create a given savefile (based on its header).
You're already doing that, just want to say you should keep doing it
![Smiley :)](https://openxcom.org/forum/Smileys/default/smiley.gif)