I went somewhat the opposite way, at least for now, but anyway -- my boat started out with a Wallas stove built in to the galley counter. I removed that, which left a rectangular hole. I then made "usable mockup from scraps" covers for both the sink and the stove hole. These were just some 1/8" ply scrap epoxied together to make 1/4" (one could start with 1/4" of course if they had it), then cut to shape. I then glued cleats to the bottom side to hold them in the sink and stove hole. This resulted in a slight "hump" where the stove one was, so not ideal, but I wasn't sure what I wanted to do ultimately. It did make it very easy to work on things under the galley counter! (Just pull it out.) I also found that the sink one made a handy sort of butler's tray when flipped (cleat side up) at anchor.
I guess I don't have photos of them in place, but here they are while I was varnishing them.
With these I used a portable butane cartridge stove, either on the counter or in the cockpit. I kept the cartridges in the overboard-vented port lazarette.
I then decided to mount a Seaward butane canister stove in the "Wallas hole" for last fall's Powell trip. This is similar to the portable stove, but "drops in" to the counter. Again, sort of a mock-up/test as it's not really "permanent" and there are things that don't thrill me about it. (I know, you're going the opposite way.) I can see why one (including me) could want a better stove, as these are not without risk. It is nice to have the counter flush again. I still carry the portable stove for backup or "outdoor" use, and still keep the cartridges in the port lazarette.
At any rate, it was pretty easy/quick to make the stove-hole/sink drop-in plywood covers, and they work(ed) great, especially considering how simple they are. I still haven't fully settled on the ultimate cooking/heating solution on my boat.... so it will evolve I'm sure.