I had the same issue - the 633 changed the balance point to be way forward because of the large wing.
I move the mast board attachment all the way back and foot straps as far forward as possible (SS Alien Air).
Still too much forward foot pressure required to maintain proper trim.
I shimmed the mast to fuselage as shown in the Delta Foils video.
It did not change how wonderful the 633 wing rides.
The only difference was reduced foot pressure required to trim the board.
The 633 is amazing and the adjustment (shim) took 3 minutes.