As one who sails a similar size and type of boat, I'm a bit perplexed by why you'd want to change to a wheel... There are many drawbacks to a wheel on such a boat, IMHO...
Looks like your mainsheet/traveler is mounted on the cabintop, a wheel will really isolate the helmsman from the main... That's ALWAYS a bad idea...
A wheel exposes the helmsman to the elements to a far greater extent than a tiller, one of the beauties of which is the ability to huddle up under/behind the dodger while steering...
The ability of the helmsman to sit further forward and outboard, on the coaming or whatever, while using a hiking stick greatly enhances your view of the sails, particularly the telltales on the headsail...
In rough weather, climbing around to aft of the wheel can represent a considerable danger, as you have to step up onto the cockpit seats to do so, placing you in a very vulnerable position...
with the narrow footwell your cockpit currently has, standing behind the wheel at 20 degrees or more of heel will likely be very awkward, and tiring... There's a good reason why most boats designed for a wheel have a T-shaped cockpit...
What about clearance between the wheel and the opening of your cockpit lockers? That can often necessitate the choice of a rather small wheel, that might be far more fatiguing in use than a tiller...
Lazarette space is truly precious on boats as small as ours. Why would you want to clutter/diminish it with a quadrant and all the other crap wheel steering requires?
On all but the very best of wheel systems, such as a Whitlock, your "feel" and feedback of the helm is vastly superior from a tiller, IMHO... Not to mention, it gives you a precise visual indication of the amount of weather helm you're experiencing, invaluable for tuning the rig, deciding when to reef, and so on...
Self-steering - whether it be a tillerpilot or a windvane - will generally be simplified when applied to a tiller...
On a 30 footer, a wheel is really gonna clutter up your cockpit when it's not being used... A tiller, just the opposite, folding it back achieves just the opposite, at anchor or at the dock...
Not to mention, that "dead space" beneath the tiller can often be put to good use for storage of deck gear, and that will have the added benefit of reducing the volume of the cockpit that could be filled with seawater... On my boat, for example, that's where my liferaft lives...
Finally, Keep-It-Simple-Stoopid... And, a tiller is about as simple as it gets...
Frankly, I'm hard pressed to come up with a single reason in favor of making such a change, but - as always - that could be just me... (grin)