I would use 23.3 for your slip %.
Yes your slip % is high at 18-21%.
The older Formula X dimensions were low at 7-8 inches below the bottom of the boat. See where yours is at.
I modified Bravo 1 is the best option. Also a adjusted drive depth might be in order.

Brett

As you maybe can see at the photo the x dim is higer then standard. And the trim flaps are mounted horisontal

Here it is :-)

Unfortunately I can't make out the drive depth from this photo.
Normally the tabs would be mounted to follow the dead rise.

It was very nice speaking wit you today.

Brett

Brett it was realy nice talking with you.,It is always interesting to talk with somebody
with that level of know how :-)
I will mail you as much info as posible, I am confident that we will end up with a good result :-) Good luck in Miami ..,

I would try a few other props, a 23" Rev 4 should keep your rpms just under 5000 and improve your cruise with less slip. My friend runs this on his 26 Powerquest with a 496 HO and gets great results, mid 60s with a nice cruise.
I also run these props and love them