Your first task is to quantify what you have now. That is you need to measure your existing setup, particularly the height and distance apart of the engine
bearers. Then find the weight of the existing engine/transmission and what access is available to put the new engine/transmission in. Note the location of the exhaust
Initially its easier to use your existing propeller
so I'd suggest looking for an engine that's similar in power and cubic capacity. I recommend including a new propeller
in your costings.
For the transmission
there are not going to be that many V-drives. I did a quick search and found one from Twin Disk. I believe ZF also makes one. You may care to substantially oversize the transmission
as there have been indications that some manufactures ratings are light on for use in a slow heavy cruising yacht. I went for about three times what was considered necessary and that doesn't seem to have been too conservative. V-drives could be a little more "fragile" than in-line transmissions.
For the engine I went with the John Deere 4045D but that could be a bit heavy for your boat. There's Volvo
and the Kubota based conversions but for a setup where space and weight could be at a premium I'd suggest looking at the Yanmar
4JH5E. I'd only consider the turbo version if having more power was a key requirement.
With my repower
there was a never ending stream of upgrades, repairs
and rebuilds so do allow for this in your budget
. I found my 2" exhaust
needed to go up to 4" and the engine/transmission "feet", fuel
system and engine controls were rebuilt as part of the project
. I also installed new engine mounts.
This is a good time to clean out and refurbish the area around the engine that is normally inaccessible.