Look at my build. It does fit. The FPP manifold puts the headpipe into the hull. You need to use a Westcoast manifold which has a different angle for the bolts. You also need to grind off the lord mount on the westcoast if using the 750 limited chamber, but not with the other chambers. With the 750 limited chamber, you need to get a longer coupler for the headpipe to chamber connection. Otherwise you need to cut the hull to allow for the space needed to use the FPP manifold. The manifold and headpipe combination is independent of the chamber.
You can put on the manifold and the headpipe and change the chambers w/o changing those other 2 things, so the choice to use FPP is one that can be made reguardless of if you are using a 750 limited, blaster or SJ chamber.
However, you are asking about the 750 chamber specifically. The problem with the 750 chamber is that it bolts to a lord mount on the front of the motor and bleeds directly infront of the motor. This means you cannot use the stock gas tank w/o significant heat manipulation of the tank. This also creates issues with many other tanks, so unless you are going with a cart tank, you are going to have a hassle. Additionally, the 750 limited chamber is designed to have an additional stainless pipe that routes the exhaust around the left side of the motor to a rear waterbox. This pipe has the water fitting you see on the end of the SJ pipes, so w/o this pipe or some modified version of it, your waterbox is likely to run hot and loud. Also, you cannot wrap the exhaust around the motor to a rear waterbox, as you cannot run a rear waterbox, so you must run it forward in a way it was not designed to the forward box. Alternatives would be to make a custom waterbox to fit into a different location.
After it was all said and done, I gave in and purchased a SJ limited chamber for my 750. I would like to run the pipe that FPP designed for my motor, but after all of the hassle, I had a exhaust system that wouldn't function as it was designed (because I had a westcoast manifold and extended coupler making my exhaust longer than it was suppose to be) and some funky exhaust routing that just made no sense. I am happy with my Westcoast 650 manifold, FPP headpipe, SJ limited FPP chamber and stock RN SJ waterbox going to a Blaster outlet. This is the method that I would support. Remember, the FPP 750 limited was designed for your motor but not your boat.
I have been through this process. I would discourage you from doing it unless you are going to make the hull modifications to allow use of the proper manifold and coupler, and get a fuel tank and waterbox that will allow appropriate flow of the exhaust.
