We ordered parts from TAD (Trans Atlantic Diesel) in Texas - their phone number is 800-927-9295. They're very easy to work with and can get the parts from the factory (U.K.) if not in stock. I saw numerous M30 parts available on their website.
There is a person in Seatlle, WA that has several used engines and will ship used parts. We've purchased some parts from him too. His name is Stewart. 800-735-7207 - Don't recall his last name but his business is called Stewart's Marine.
We just finished re-installing our Prima M50 after completing a thorough hose, timing belt, water pump, idler pulley, rear engine seal, transmission seals, heat exchanger cleaning and new gasket, and countless other preventative maintenance cleanings. Konami's engine has 2400 hours and is working well so we decided to keep the engine and do a clean up to last another 4000 hours.
Let us know if you have any questions, I've chased a lot of parts and got what we needed.
Diane