I still stand by my theory that, done right, Extreme Ghostbusters in GB3 could work. I mean, if you look at Darkness At Noon, its pretty much an hour long version of what GB3 could be. Expand it to one more hour with more character development and input from Ray, Egon, and Winston and you could have the Indiana Jones and the Last Crusade of the GB movie franchise. Plus, you can always bypass that whole Murray problem by just explaining it away in a scene that makes sense.
There, my rant is done