Yes, there should be no strength or failure issues with using a 50 cm std. Tuttle fin in your
deep Tuttle fin box.
You will need 2ea. 20mm longer fin screws to reach down to the barrel nuts (brass threaded
slugs) that are pressed into the fin.
The normal change over from std. Tuttle to Deep Tuttle fins normally occurs right around 60 cm.
Using a 60 cm + fin in a std. Tuttle box begins to introduce a risk of fin box failure unless the fin
is fitted to the box very carefully.
Hope this helps,