Hi.
Welcome to the forum........Ne'er a post about a 314 Sprinter in years on here and 2 posts in a matter of days.
So see my reply in this very recent thread containing a link for a replacement engine ( yes I know its far away ! )
http://www.mbclub.co.uk/forums/parts-maintenance-servicing/215991-sprinter-314-petrol-2004-a.html
You will see that the 2.3 NGT M111.984 petrol engines for these vans are very rare and therefore there will not be a great deal of folk ever having swapped petrol engines.
"Will a "C Class M111.xxx fit ?" Who knows you might be one of the first to try, but given the time and inclination most engines can be persuaded to fit. Many moons ago I put a SAAB engine into a Reliant 3 wheeler, so anything is possible.
Engine mountings, sumps and oil filters can be a problem, but can be overcome by using your original engine components. Clutches and flywheels can be swapped and check also the engine /gearbox mating holes. A big hammer is useful, as is some welding Kit.
How bad "finito "is your engine?? Is it possible to rebuild it ??
If the problem were mine I think I would rip out the engine, stick it in the back of the car / van and go find a M111.xxx petrol engine in a breakers yard and put them side by side and see how different they might be. You might be lucky and just get away with using the block and pistons you might not.
The Diesel engines such as in a 312 are canted over on their sides, is the petrol engine like this? This may affect your choice of engine as I presume petrol engines in the cars sit up straight.
There is much to consider, although fortunately there is plenty of space in the Sprinter engine bay for you to work with. There are those on here that would have you fitting a 5 Litre V8 complete with Supercharger !!
Which ever way you go it would be useful for other poor souls in your situation if you can report back on your progress (with some photos would be handy). I wish you well in your task.
Steve.