We used to have a twelth share in an ownerships boat and that had a bmc engine it.
It had run out of hours on clock but was still reliable ownerships kept trying to talk us into
a new engine but we used to argue that you don't have a new engine in your car just because
it hits 100,000 miles.
Our current boat has a perkins D3 in its own engine room much easier for maintance and warms
the back cabin a treat and drys wet clothes out .
Ultimately personal preference and how you intend to use your boat.