A friend has an Ericson 33 that originally had a wheel and is now tiller steered. This boat's rudder stock has a top bushing and exposed shaft nearly at deck level so attaching the tiller was a simple matter.
He does have a circular hump in the cockpit where the original pedestal hole has been covered with a gasketed plate, but generally it's not in the way of anything while sailing. The original quadrant is still on the stock below decks, but again not really in the way of anything.
Wheel-to-tiller will obviously be less costly than going the other way, esp if you can sell the pedestal later on.
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)