Hi,
When I bought my Westsails (in 1974 and another in 1975) I had to deal with the engine issue. The Volvo diesels are marinized engines, as are a number of others. The cost of developing engines is enormous, considering the limited sales potential. Not all marinized engines are in my humble opinion suited to be used as a marine diesel. Here is a stab at Volvo: I needed a spare part in August, but their warehouse did not have it, and the Swedes could not ship it because of their summer vacation (at least that5 is what I was told). My Volvo MD3B (Marine Diesel 3 Banger) had a leak from the coolant pump into the crank case, causing the oil to be contaminated, rusting everything.
I did not hear anything negative about the Beta Marine Diesels, I understood twenty years ago that they were a marinized version of the VW diesel. The VW diesel was originally a gasoline engine that was converted to have a very high compression ratio. I owned two of the Golf diesels, but did not like them as they were too complicated to repair by myself. Looking into Wipedia , there is a mention of Isuzu making an engine for Beta Marine.
That tells me that Beta Marine (abbreviating the company name would be disrespectful) has been buying the blocks and adding things to make it into a marine engine. I have not looked into the company's website but by the limited offering on the marine market, I may assume that there is a interest in providing a product that generates customers goodwill because Beta Marine may not that be big a company.
What did I buy to replace the Volvo? A Faryman diesel. I saw these guys setting up a Faryman 32hp in a refrigerated trailer and asked them about the crazy location for an engine, they replied that they are demonstrating the engine to be handcranked for Coast Guard lifeboats in freezing temperatures. So I bought one after the cranking worked. Faryman is still in existence, but they do not make that engine anymore. Another that seemed interesting was a Sabb one or two cylinder diesel that I remember from my year on an North Sea island. It was the ancient ker-chanka-chanka vertical contraption that was always started with a hand crank. Another reason I bought the Faryman is that there were classes on repairing it. Since you have bought the Beta Marine already, try to locate a course in diesel engine repair. I would have never attempted to fix the rusted fuel injection system of the Volvo with what I know now.
Voytek, knowing who made the engine components is important. What I have seen from the other manufacturers, you need to find out what was made by Beta Marine or who made that block and the head, piston, crankshaft etc. I hope that you do not have to field strip the rusty injection pump like I did and keep the parts really clean and put them together in the correct positions. But that is another story.
Happy detective work!
MZ