Hello from the land of snow! I'm so jealous you live in the caribbean, and I'll probably not be the first member on the board to tell you that!
You've got a very interesting situation, however I would not look into replacing the engine with twin outboards. It will end up literally destroying that boat. The Z302 is a beautiful boat in every aspect, we'll help you figure out what needs to be done.
First off, we'll need some information.
-What motor is currently in it?
-What makes you think it's shot? (Does it just not start, or does it have a piston sticking out of the block?) Did it ever run?
-Have you tried locating a service facility on any of the surrounding islands? How far southeast are you of the Bahamas? There has to be someone with sterndrive experience around you.
-How mechanically inclined are you, is it engine repair something you feel confident enough you could do yourself?
Secondly, let's consider the options.
-Engine Repair - If you can find a shop that's capable of repairing it, this will most likely be the easiest thing. They can pinpoint and repair just the part you need replaced.
-Engine Replacement - You can buy replacement or rebuilt engines from many different sources, including Mercruiser. This involves removing the existing engine and mounting an identical replacement in it's place. This is most likely the most cost-effective solution as you won't need to change things like engine mounts, transmission and driveshaft adapters. You remove your existing motor, mount the new motor in, and reconnect all your parts. It's pretty straightforward if you've got an exact replacement, a Mercruiser Service Manual, and all the tools to remove the engine, including a hoist.
-Repower - Depending on what motor was originally in the boat, you may find it beneficial to repower by choosing a completely different motor. A few of our European members have swapped out their Gas engines for Diesels due to the fuel constraints. You can also swap for a larger more powerful engine, or a smaller engine. However with the Z302 I wouldn't recommend anything less than a 5.7L engine as it will be grossly underpowered. There are many companies who make aftermarket engines, including
Crusader, who make a pretty good product based upon what I've seen. Choosing the Repower option will definitely be the most expensive option available as there is a lot of custom work that goes into this. However, if you plan on keeping the boat for a while, it might be the best option.
Also, did a search on the Mercruiser Website, you might want to try and contact this dealer.
Sherlock Walkin & Sons
P.O. Box 583, Blue Hill Road
Providenciales
Turks & Caicos Islands
Phone: 1-649-946-4411
Fax: 1-649-946-4945
walkinmarine@tciway.tc
Good luck with it, and keep us all updated!