The spimlest answer is; I don't know.
I'm working on it though, after a bit of looking it doesn't seem that the Great Options Mod will have any conflicts with RFC (Beyond Compare 2 is the greatest program
EVER. Seriously.)
It is with great pleasure that i announce that I have just, for the first time in a few months now, loaded up CodeBlocks, loaded the Civ 4 SDK into, and hit Build*. Hopefully before the night is out I will have a working version of RFC Epic merged with the Great Options Mod to give you guys.
NOTE: this will only be the vanilla version. The Great Options mod only comes in Vanilla Flavour apparently, so I will have to convert it over to Warlords and Beyond the Sword myself. It doesn't look like it will be too difficult, as TheLopez is a genius when it comes to documenting his code, but if I do run into problems it will likely be several days if not weeks before I solve them, as I am not nearly as good of a programmer as I would like, and the SDK is reall complicated. As I said, I am hoping there are no conflicts.
*Story abridged for dramatic purposes, I actually needed to change quite a few settings first
.
EDIT: So, yeah. When I made the 'by tonight' claim, I hadn't quite looked at the python code for the Great Options Mod. Now, its confusing, even before factoring in that I don't actually understand anything about Python. This may take me a coupe of days.