If you're handy at fabrication it wouldnt be a problem. It really doesnt need to be bolted to the engine, it could be on a stand or bulkhead, so vibration wouldnt be an issue. It does need to be big enough and able to flow enough raw and fresh water to get the job done. Heat rejection calculations are available to check that. Most folks think diesel engines and associated systems, very much especially marine diesels, are akin to rocket science. It just aint so