Hi, Nate. I don't think you're the first to explore this conversion, heresy or not. My standard O272 is the outboard version and lake-locked and I prefer the outboard to the diesel, for various reasons. It's easy to service, easy to replace, uses a very small amount of gas over the season (Tohatsu 9.8 25in. shaft/elec. start) and pushes a lake boat quite well. I admit, it isn't as clean and sleek looking at the stern as the diesels, but it's more practical for my needs. The local diesel mechanic hits you with about $100 just to travel to the slip, then the meter starts running. The engine access in the 272LE doesn't seem too bad, but an outboard beats it every time from the standpoint of simplicity.
I'm not sure if O'Day did anything to beef up the transom on the o/b models, to accommodate the added weight in a concentrated area. I swapped out an old motor mount for a new model, to take the weight of the four stroke replacement, several years ago, and didn't notice anything unusual on the starboard side transom. The mount is located on a block and appears to spread the load across the starboard transom area But I do wonder if there would be an issue with the pedestal steering system and its exit location on the transom when trying to properly position an o/b mount. My boat steers via a tiller/rudder setup and my only concern is to not turn the motor and rudder into to each other, as they'll make contact (the prop usually wins, in this case). You'd have to send someone small down the starboard side lazarette, because it is tight. Add a gas tank, hook up the motor wire harness to charge the batteries and provide electric starting, and that should take care of things. But, do you leave the diesel onboard or not? Its a lot of needless weight and a clean uninstall would seem to be the way to go. Decisions, decisions. It might be best to try and find someone in your area with an o/b model and study the differences carefully. If mine was at the coast, I'd keep the diesel, but I'm not and the Tohatsu works great. Good luck.