Got that SWU nostalgia bug, huh? As the kids say, I know them feels.
I tried to get a game going with a very similar theme a while back, but at the time there didn't seem to be a lot of interest, and the project was largely abandoned. That said, it's a theme I'd love to play in again. PennMUSH, D6, Rebellion era, NPC Empire? I'm into it.
The following is purely my opinion, take it with a grain of salt or ignore it completely.
WEG does not do the Force mechanics well. There are arguments on both sides of this, but WEG, especially on a MUSH, tends to be very unbalanced when it comes to the Force. Not as big an issue in a Rebellion-era game where there are practically no active Jedi, but still a concern, because...
As said, people want to play Jedi. It's one of the biggest draws of the SW theme. Flatly stating "No Force" is going to shoot you in the foot, in my opinion. Maybe you start off with no Jedi, but work toward introducing them through plot machinations. In both Canon and Legends, there were active Jedi during the early years of the Rebellion, but they were a) rare, b) either smart or short-lived.
SW games also don't tend to do well if there's no space system. Players like their stuff; coded ships, weapons, armor, etcetera, even if it's basic. A space system that gets the player from planet A to planet B without much in the way of frills is probably enough, and weapons/armor/equipment that gives the player some stats to reference will make them happier than just saying "just roleplay it".
Not sure if it needs to be said, but in my experience, limiting a SW game to a single planet is like signing its death certificate before it takes its first breath. You might get away with a somewhat isolated sector in the Outer Rim (Brak Sector? Minos Cluster?), but I've always found that players want familiar planets like Tatooine, Corellia, and Coruscant.
The smartest thing you can do is make the Empire an NPC faction. One of the biggest struggles I've seen in SW MUSHes is the balance between the Rebellion "losing" and the Empire "winning", (which is patently ridiculous, but that's another story); the Imperials always complain when the Rebellion wins, because it's "unrealistic", or the Rebels always complain when the Empire wins because "we're supposed to be the good guys". To say nothing of the fact that managing a PC Imperial faction is a logistical nightmare.
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Anyway, that's my three cents on the subject. If you want to discuss further, send me a message. If this gets off the ground, I'll definitely give it a shot.