Having put a new engine into Boracay I can only endorse what others have said, particularly with regard to the exhaust and waterlift muffler
. It's only money
You may also have to put in new engine mounts and raw water
strainer. This would be a good time to do any necessary upgrading of the fuel
There are so many reports of gearbox
problems that I'd suggest going with the largest practicable gearbox
. I went with the ZF63 for only a few hundred dollars more. Massive overkill but hopefully it will never break.
I went with the Deere 4045 (Good local support) as Yanmar wanted their own people to do the installation
. It's bigger and heavier but the extra power is nice.
All other things being equal I'd suggest going with the engine with the largest cubic capacity.