Unless you buy a new engine, I would avoid DFI engines(OPTIMAX, ETEC, HPDI). Parts for them are just to expensive IMO when something goes, and your pretty well limited to the dealer for diagnostics due to the cost of the software to scan them. For that kind of money you could buy a late model 4 stroke, but be careful of corrosion on the YAMAHA's as it seems they are experincing internal corrosion that rots from the inside out so you don't see it until it's to late. A late model 3.0L 200/225/250 MERCURY would bolt up using your same controls I believe, and aren't to bad on fuel as well as being powerful. I like the 88-92 OMC(not a huge fan of the 93+ engines due to the castings corroding internally when used in saltwater) V6's. Packed a good punch, not horrible on fuel, and cheap to work on. Problem is parts are getting harder to find for them, and what parts you do find are getting up there in price. The YAMAHA OX66's were some good engines as well, and the OX66 fuel injection had a great track record. I would avoid SUZUKI for corrosion reasons due to there aluminum being pretty poor.
The biggest question is do you want to go newer technology, or stick with something you can work on yourself. I would think for $10K you could find a nice shape YAMAHA 150 4 stroke, and I know you can find late model EFI MERCURY 225's for around $5K and reuse your controls(and I'm pretty sure your harness will work also).
EDIT:I just remembered your boat is a bracketed center console. I would stick with a YAMAHA 150 if you want to go with a 4 stroke, a 150/175 YAMAHA OX66, or a 2.5L MERCURY 200HP outboard for weight reasons. Gotta be careful how much weight you go hanging off the stern with your combo offshore.