Yeah... that's what I was thinking. The Sith Empire of Zakhull was way back during the Great Galactic War, with Emperor Valkorion dying at 3637 BBY (Before the Battle Of Yavin). The Galactic Empire was formed thousands of years later in 19 BBY. So while technically they are in the same Universe, both Empires are extremely far apart time-wise and different enough to be their own thing...

We also have the whole Disney Charade as well so... I'll have the Empire be mostly Canon, but with some EU items with it just for its sake.

I would pick something a bit more unique the First Order or the Yuzhan Vong, but either we have barely any information about the former or the fact that the latter are OP as hell.