Years ago we had the use of a CTS 70' with an Ailsa Craig RF4 lump in the middle. Far and away too big to be sensible, impossible for spares.
A lovely free swimming boat, did 2mph as soon it was in gear at tickover, cruised at 180 RPM and was a nightmare to use at times.
Could never run it hard enough to clear the carbon, threw red hot carbon clinkers into your face all day.
Eventually on the Bridgewater it started to knock, due to carbon build up. Ended up being towed back to its mooring for repair.
Accommodation wise climbing around the flywheel to get through the boat was difficult, impossible when underway.
Convinced me that as a live aboard I needed an engine under the floor not sat where the bedroom should be.