I am also from DK, but guess we better keep it in english :-)
I weigh in at 87 kg, and have the 2009 FUTURA 122, which should be 117 l.
Excellent board ! Very fast free-race board, that just flies above choppy waters.
My largest sail is a 8.0 V6 2 camber, and with my technique/weight 12 kts are well below planning, but with your 80 kg + 8.7 sail you will be close to planning.
The smallest sail I use on it, is a 6.2 HELLCAT, but the 6.7 HELLCAT is the sweetspot combination for this sail/board.
If you will be sure to plane, then you might consider the 133 FUTURA, which have had excellent reviews as well.