First, there is not one for that change. It has been done at least once that I know of and when the owner tried to sell it, it created a sh*t storm of additional paperwork. Re-creating that paperwork may be easier now that the initial hoops have been jumped through, but the cost would still be astronomical.
All that being said, the IO346 is a good strong engine if properly maintained. Overthaul is possible as long as the case is still serviceable. After flying one for 12 years, I would buy another one if the engine was not more than midtime and in good shape.