We've got two Perkins 6.354s which have not been maintained much in their 32 years / 1040hrs. Mechanics and surveyors who know these engines, like them; plenty still around.
I understand that, that when I get the deferred maintenance issues taken care of (overheating over 2200 rpm, dirty fuel plugging the Racors, the remaining original hoses replaced) all can be expected to be well.
In 1993, I crewed on a 1968 Columbia 57 (sloop designed by Bill Tripp) bringing it back to Boston from Charlotte Amalie, USVI, where it had been a marina queen for several years. Perkins diesel, wonderfully foul fuel (we'd pumped all the old fuel into one of the six tanks and put fresh fuel into the remaining five), lots of Racor filter elements, newly rebuilt injectors. On the 6 day passage, that engine failed on a daily basis, requiring filters, bleeding, threw a valve pushrod twice (hammered it straight and reassembled it each time), blew one cylinder's fuel line. I was hero for a day or so when I took a loose steel fuel line from a long-gone genset, found in a pile of stuff in the forepeak; I repeatedly heated portions of it to cherry red on the gas cookstove and bent it to fit the Perkins. Other adventures were enjoyed on this passage, too.
Still bought the FuHwa with the Perkins.