I think the Edelbrock MPI kit is over $1K. When I mentioned this to my local ski boat mechanic, the answer I got, and the answer I hear most often, is that it just isn't worth it and if you want a fuel injected boat, sell yours and buy a fuel injected boat. Like Dan, I'm not mechanical. But this has been the consensus from the people I trust most on the subject.
If you're looking to spend $500, spend it on a Holley 4160 single feed marine carb. Greatly improved reliability over the 4010 you have on there now IMO.
Previous: 1993 Prostar 205
Red 1998 Ski Nautique, PCM GT40, 310 hp, , Acme 4 blade, Perfect Pass SG/Zbox.
Be kind. Have fun.