It doesn't sound all that hard to do, if you reinforce and extend the rudder post, re-mount the engine controls to the port cockpit locker, and find a new place for the compass. I'd be sure to regularly check the welds and for corrosion on the rudder shaft, however, as the bottom of it is open to the sea. Otherwise, to get a continuous rudder shaft, you'd need a new rudder.
I sailed dinghies for 20 years, and have owned two tiller-steered boats (a modified prototype Seafarer Meridian and a Morgan 28 k/cb). I now sail a PSC 34 with a wheel. I wouldn't go back to a tiller.
This has a lot to do with my cruising style, which is usually singlehanded, and is in Maine where I can get help if I have a real problem. Also, I rely on my gps/radar combo on my binacle. I ran for 2 days in dense fog last summer. I wouldn't have done it without a radar by the wheel. Those lobsterboats don't slow down for a little pea soup!
If I cruised with a partner, in far areas of the world where self-sufficiency is paramount, the equation might be different.
Here's my reasoning:
I agree that a wheel has more that can go wrong than a tiller, and that the steering gear on a PSC 34 is about as inaccessable as it can get, but with regular inspection and occasional maintenance, I would suggest that the quadrant/cable steering is one of the most inherently reliable systems on a boat.
It is true that a tiller takes up less space than a wheel/binacle when at the dock. I mitigate that by dismounting my wheel to a spot on the stern rail when entertaining guests at the dock, but they still have to climb around the binacle.
BUT, when sailing, the tiller takes up a lot more space than a wheel. Much of the time, you have to keep the entire space where the tiller might swing clear. Otherwise, people will get banged knees and you won't get the rudder deflection you might need to maneuver.
In a PSC 34, this would be almost the entire cockpit. Furthermore, when tacking the boat, you would be trying to do the limbo through the same spot that your crew would be using to release the windward jib sheet and trim the leeward one. If you had to maneuver, your guests could sit on either side of the tiller head, but that would be about it.
In addition, there are other considerations:
The wheel is less tiring to steer with over the course of a day. Not only does less attention have to be paid to steering, but you don't have to have an arm out, gripping the tiller, all day. As a person with a bad back, who has trouble finding a comfortable position, a wheel gives me more choices, and more comfortable choices, for steering position.
The wheel is easier to leave for a few seconds or a minute. If you're alone, with a tiller, you will have to use a limiting device or engage a Tillerpilot in order to do anything that requires that you drop the tiller for more than a few seconds. The PSC is a lot more directionally stable than my prior boats, but even so, there is a huge difference in convenience. With the wheel, I can dial on some tension to hold the rudder position and walk away for up to a minute.
The wheel is easier to use for guests and other inxperienced boaters. This may not sound like much, but if you are incapacitated, or just need to go and use the head, and your crew is either inexperienced or, like my ex-wife, who was unable to deal with a tiller dispite her best efforts, you won't have anybody on board who can steer for you.
The wheel uses more sophisticated autopilots that are easier to use. Attaching a tillerpilot on a bouncy day takes a little dexterity, where I can just hit a button. Also, the tillerpilot is not as sophisticated as the below-decks units. Unlike a tillerpilot, my belowdeck unit can sail a decent chose-hauled course. Of couse, you might be able to retain your quadrant and use a belowdeck autopilot, or a windvane for that matter, so this may not be a factor.
The wheel offers a better place for controls. If you have a tiller, your engine controls will likely be down around your ankles, where you can trip over them, sub your toes on them, or step on them. I lost count of how many times I stepped on the throttle of my Morgan and unexpectedly ended up with full throttle. It even happened while I was docking etc. I never got into trouble, but I often had to look away, stop what I was doing, and reach down into the footwell to reset the controls. In addition, the controls had removable levers, which I was afraid of losing in an emergency. Furthermore, the binacle-mounted controls are easier to get to in an emergency.
The binacle offers a better place for your radar/gps. I frankly don't know where else a singlehander could put one but on a binacle. As a singlehander, I can't use it down at the nav station and I just don't see mounting the screen on the back of the cabin.
The same goes for the compass. There are plenty of places to mount one, but the prefer the binacle - it can hold a much larger, and easier to read, compass. This is important when my glasses get covered with spray. It's even more important when I have to take them off becsuse of the spray!!
A tiller does give you a much better "feel" for the boat, and is often more satisfying, but for both safety and convenience and given my cruising style, I'll take a wheel.