Thanks for the feedback as it's been super helpful. I've decided to ditch the FI and order a new carb and just enjoy the boat until the thing grenades and then build up a good motor. It came with a 650cfm but needs an 850cfm, so I'll put one on and call it a day. Thanks for the input!

I know you've all ready decided to go the carb route but let me give you another data point for the future. You would be able to install all the EFI stuff from the old motor and get it running, even on the stock tune. Regarding distributor installation you would need to set base timing, which is usually around 8 deg BTDC for Merc motors. Setting base timing is easy.

The stock tune should be sufficient to get the motor running in a stable manner on a test stand, but it most likely will not be ideal. To get things working properly you would need to have the fuel table and ignition table tweaked. You either pay someone to do it or get the software and do it yourself. You would also need wide band O2 sensor installed to get AFR data.

Lastly you need to know what your current injector size is and calculate the max HP those injectors can carry at 80% duty cycle. If you are deficient in that area you should step up in injector size.

In summary your big cost going EFI are:

1) tuning (software) doing it yourself ($600 ish plus your time and learning curve) or paying someone else to do it ($??????)
2)Wide band gear ($200-400)
3)Injectors ($400-800)

I'm not trying to sway you one way or the other, but it can be done, even by a layman IF you take your time and think things through. The learning curve is steep but I found it rewarding.

Now THAT'S the information I was looking for from the beginning. Thanks for laying that out - much appreciated.

I wish you the best of luck regardless of the route you choose.

Did you change the cam?
It says 246 DURATION @.050 ON BOTH THE INTAKE AND EXHAUST
Unless your exhaust is dry to the tips you are going to have problems :(

They are through the transom with those flappy things on them. What problems should I expect and what time frame? Immediate? Over time?

I appreciate the heads up on the matter.

That cam is going to suck water back up your exhaust at idle and seize/hydrolock your engine.

Ah. Well that's a bummer.

So the top end of this motor looks all wrong and cheap for a boat motor, but any opinions on the bottom end? Worthwhile platform to build off of?

Cast crank, depends on what you want to do with it.