A turbo is a bad idea for any normal use boat, no matter what some our less learned members have to say. For a small boat 2.3 based turbo you would need an open engine bay, due to the high heat generated, and weigh less than about 1500#. Turbos don't generate low end torque and since you ain't getting onto a plane without that it would be useless. I'm assuming here that your on plane cruise rpm is in the 2000-2500rpm range, turbos normally don't start making power until 3000rpm. I can't imagine wanting to stress an engine with a turbo and then expect it to live at 3/4 throttle for hours on end.
Upgrading to an electronic ignition is a good idea but, don't discount points too quickly. They are dead simple and will get you home everytime. Maybe put some thought to adding an MSD box. Then even if it does crap out you can rewire it in 5 minutes and be on your way.
What carb do you currently have on there? I've seen the OMC 2.3 motors but never paid attention to the carb. Depending on what way you want to go and how much money you have to throw at this, a '85-'88 Ranger and '85-'91 Mustang lower intake manifold can be adapted to fit a Holley 390cfm 4-bbl. It works very well on the 2.3 and can be marinized easily.
One minor addendum to my earlier post, to put the 2.5 short block in your boat you'll need to use a '89-'94 2.3 block as the later 2.3-2.5 blocks did not have a provision for a distributor.
And just to assure you that I do have some experience in these matters, I'm currently running a 383ci Chevy motor on my '87 Cobra drive w/ 22" 4-blade SS prop. It's been doing very well for quite a few years now. So I know 2.3's and I know boats.
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