I'd be THRILLED to get Halloween III over Creepshow. They better not force Michael into the house unless it's little nods (like maybe he can be seen in a window or two with the musical queue playing over the rest of the scene for a quick 2 seconds) or a bonus room / post house scare type thing at the end that doesn't affect the narrative of the movie.
I mentioned in last year's spec thread I think, that a full original mashup could be cool where the masks are killing people/kids in the beginning of the house and then a mask kills someone Michael was about to kill so he gets pissed and goes on a rampage at the Silver Shamrock factory for the back half. That wouldn't be bad, but they'd have to name it Michael Myers vs Silver Shamrock or something like that and not call it Halloween III Season of the Witch. Of course, how Michael would have made a 30+ hour drive to California is another story (I think Part III is in California vs Illinois).
Regardless, the GP who don't know the movie would be confused by the story line and why we had 1, 2, and 4 at the event previously and are now going back to do 3. So anyway you cut it, there would be some confusion and disastisfaction, that just means shorter lines so fans of the movie can get more runs through it.