i just did mine this week...from my research everybody did 3" radius from stock length (which i believe is 330 mm).
I used a stock plate, and measured the center of the plate...cut a 3" string attached it to a marker and made the circle....drilled some holes in it the with a jigsaw cut to each hole...sanded down.
so after my novel...i choose choice A lol. sofar i love mine...nose real high out of the water...ski pops right up when you're trying to bunnyhop. however...it will slide out on you alot (as i found out today when i tried taking a turn in the marsh and landed 10 feet up onto it)