I got myself a 92 Litre Tabou free style wave board that came with a 24cm fin. I mostly use it with a 5.7mt in bump and jump style conditions ocean / choppy harbour etc. I have been suffering a lot of spin out and decided to get a larger fin.

Fin arrived yesterday and went to go for a sail today but the head was just a little bit too big!

First question is how many types of US box sizes are there?

Second question is how to make it fit? Do I drill out or route the fin box on the board or attack the fin?

If I do the board can I simply drill the hole out a bit and then what do I coat the newly exposed area with?