One thing about sailing at Inverloch it makes you lazy

Sail to the nearest sand bank, do the famous Inverloch step gybe(step off the board and turn it around) and sail back!
So I am about to invest in a new Patrick 135 Free Ride board and need advice on fins
I am 85 kg been sailing for 10 years
I plan to use this board for 2 reasons.
1) Light wind(10 - 12kts) with 8.5mtr and 7.5 mtr sail
2) Learning board(12 - 15 kts) for non planning and planning gybes with a 6.6 mtr sail
For situation 1) I was thinking 46cm and 40 cm fin
For situation 2) I was thinking 36cm fin
I have been a C3 Venom fin user for years and loved them - however they are no longer I believe
So what brands names should I consider and is my sizing correct?