Chris its done already SBI put the new engine spec in the 2015 rule book, and there are 3 being built right now.
Pretty simple platform, similar to the Superboat Class motors. Less RPM 9.0 instead of 9.5 , all the specs are there.

Chris, 1 other point is u dont even have to sell your 525 you can convert the 525 pretty inexpensive. You will have plenty on parts to sell ,comp , intake, cooling system and so on.

Leave Mercury Racing out of it!
one talking point that is always at the top of the discussion is price. Remember, it was Mercury Racing trying to force everyone to buy their newest/latest engine every other year. The result was, it killed Factory class and led to a huge fracturing of the sport. SO, my advice to you all is quit turning to the Mercury Racing for your only engine option.
Learn from the past, lest history repeat itself. Again!

Who else makes a 550HP motor that has fresh water cooling and a smart craft type system that has a great track record for reliability and cost? Also if we are looking for something new IMO we don't need less HP to go no faster than 90 MPH so we can have something even more reliable and save on our drives as well. That is if cost is really what this is about.

Good example is the Superboat class motors. Cost to race a full season is half what Merc 750 12:1 comp hand grenades were that the class ran for yrs till they finally made the move. Reliability doubled, Superboat teams are running a full season on a pair of motor, and then fresh power for KW. The nice thing about the motor are simplicity if they dont start it's fuel or ignition. Being part on the Byrider Team i have learn quite a bit about those motors. I guess it goes back to the old saying keep it simple stupid. Another plus is for teams with older boats that have trouble making weight the engine has about a hundred and fifty pounds lighter then a mercury 525. Also much easier to tech with MSD ignition vs using the box that mercury uses. The MSD ignition is also a great tool parity it's very simple to lower someone's rpm by replacing a chip. Just things to think about for the future.

How do you tec the heads, cam, carb and rotating assembly?

Specs are all in the book. It's specifies the parts you have to use. Something you have to realized at 509 cubic inch and 9 to 1 compression and RPMS you can only make so much horsepower the cams that are specified for the Motor will give you the max horsepower. There is spec intake carb is open 4150 style only. Its air in air out, that's why the super cat motors made so much horse power because they were 12 :1

It worksSBI tec's super boat motors and the super boat vee unlimited we are not reinventing the wheel just going with what works already.

You are 100% correct going from the HP500 to the 525 was the beginning of the end.

Also if memory serves me correct the same exact thing happen to the super cat class when Mercury tried introducing the 850 and discontinuing the 750 the class split and evaporated