I had a single Perkins T6354 (turbo with aftercooler) said to put out 175hp, in a previous boat. Utterly reliable during my ownership,and it had done many (unrecorded)hours in the hands of a large Sydney sailing club (CYCA). Parts,at least for the turbo itself, were an issue, a new cover for the turbo had to be fabricated out of s/steel locally.
My present boat has Ford Lehmans, non turbo 2715E models, 6220cc, producing 120hp. Some later versions produce 135hp.
The Lehman engine book I got with the boat also lists a turbo 363 cu/in or 5950cc model 2704-ET/6D363T producing 150 hp @2400rpm, but not the 265hp version you identify. Assuming that version, coming later, uses a similar size block to produce the extra hp, it must have been heavily tweaked to do so.Whether that affects reliability other Forum users will soon tell you, but Lehmans in general are big heavy engines with a reputation for longevity,at least in non turbo form. BruceK