If it's just a matter of removing someone else's retrofit, it could be very simple.
One thing to think about, if the the wheel is at the rear of the cockpit (over the rudder post?) a tiller would move the helmsman position to the front of the cockpit. Which is a more sheltered spot in inclement weather, and at least for my boat, right over the engine exhaust standpipe, which creates a warm seat! No, wait. That's not the one thing.
The thing is that when you move the helmsman position, are the sail controls still within easy reach? And the engine controls too, for that matter. If you have to move everything, the job becomes more complex.