Kode 80 or 86

[davidza2006]

Hi,
I own a Mistral Naish 8'4 from 2000 (waveboard 74L, 53.5 cm wide, 6kg) that I was using as my unique board from 15 knots with 5.3m2 sail when my weight was 65kg.
My weight is now 75kg and I hesitate between buying a Kode 86L on top of my Mistral or buying a Kode 80 to almost completelly replace my Mistral.
I want to be able to planning from a good 15 knots on flatish salt water, and have a good level (all jibes, front/back loop, speed loop, surf...)
Is planning from 15 knots with a Kode 80 and 5.5 or 5.7 sail not realistic? (could I even put a bigger sail without feeling it too much)
The sail I use the most is 5m.
Thanks for the help
(PS I will buy a wood carbon)

[PrydeMan]

I go for k86 for this light winds