How much actual shotgun shooting do you do? Do you shoot clay targets regularly (3 or 4 times per month or more)? If you haven't done a lot of shooting, you may be wasting your money on a detailed fitting. The reason is that if you don't shoot much, you haven't really established a shooting style/technique that is "yours".
You might spend hundreds or perhaps a couple of thousand dollars getting fitted and having the guns fitted to you, then you start shooting regularly (often) and change your shooting style to a better style. Guess what????? The guns will no longer fit you.
If you haven't established a good, solid shooting style or technique, I'd recommend you save your money. Get the LOP, drop, and cast somewhere close to what you need and take a few shooting lessons. Then shoot A LOT before spending big $$$$$ on professional fitting.
If you already shoot a lot, then it still wouldn't hurt to have your style/technique checked out by a good instructor before spending the big $$$$$$. Good luck.