Have a look at my post in the efi section
http://www.lextreme.com/forums/showthread.php?t=1687
Use an aftermarket computer - that way you are not limited when it comes to tuning it. Also there is a lot of extra crap (emmisions ect) that you don't want or need in a boat - especially with all that water around.
I used an Autronic on my lexus powered boat because they are one of the top range systems and they make a specific waterproof model for boats.
Off the top of my head, you need cam position sensor, crank position sensor, fuel rail pressure regulator, injectors (may need bigger ones than the standard factory one for forced induction) throttle body(inc throttle position sensor) coils and distributors off of the original engine.
You will also need efi fuel pump, probably some sort of surge tank built into your fuel tank, efi fuel filter, 2 ignitors to drive the coils
The computer you buy should come with air and water temp sensors.
Thats to run the factory twin distributer setup.
Alternatively, I think Ray removed the factory distributers from that engine so you could run individual coil packs if you wanted to - probaly more expensive though.Dont run waste spark setup on forced induction!!
You can also set up your own cam and crank sensor rather than use the factory ones if they aren't there anymore.
I would look at buying a cheap engine from one of the importers (or a blown one off someone) to get all the sensors if you don't have them anymore, rather than **** around trying to make crank pickups and things up.
Aprox Cost -
Autronic SMC waqterproof version inc. loom and ignitors $2100 (guess)
Fuel pump filter lines ect $400
sensors, fuel injectors, fuel rail, ect. you are missing, or cheap complete motor ($500)??
Pay someone to tune it ???