41 cm is fine in Std. Tuttle.... plenty of fin head to fin box integrity and strength.
Std. Tuttle in a Deep Tuttle fin box is fine, but you will need longer (18-20 mm) fin screws!
Might have to do some minor fitting and/or shimming to get the fn head truly flush with the
bottom of the board/finbox. Be sure to leave the fin about 1/32" (1 mm) proud of the bottom of
the board as "draw" to really seat the fin head in the tapers of the fin box. Pull it flush with the