Hammon, you need to tune (or rather, de-tune) the organ! The 850 has a main and ensemble set of oscillators (in addition to celeste). You need to tune the ensemble a little off normal tuning to get a little chorus going when the flutes are played against the diapasons.
However, there is NOTHING wrong with using a Leslie in the chorus mode with this organ. I believe the tabs are built in to do this.
There is also an "activity" adjustment, and increasing this will give a random effect to the tuning, which might satisfy your desire for some motion. It's located on the Tremulant Generator board (Rack 1 position D).
If you don't have a digital reverb on the organ, I'd recommend adding one. The TC Electronic M350 is a pro-quality unit (meaning "CLEAN") and sells for around $170 street price. It also has effects. It adjusts with KNOBS, so you don't have to learn how to program it--you just set it the way you like.