hmm, so generally the trend for team riders or even ourselves personally is - stronger winds/small board = Grip for making the most of the better/more hard core conditions. And then for the lighter winds/more onshore and tricky conditions, a faster planing board like a Mamba or FreeWave. For your skill level sounds like a Grip/Mamba combo would be ideal.
If you don't mind a bit more volume then 86 Grip plus 104 Mamba would be a good option. If you think the 86 is too big on the windier days, then maybe 82 Grip and 94 Mamba. 6.3 is a bit big on the 94 Mamba, which is why I would tend to go for the 104 instead.
The Grip 82 vs 86 - common question here. So both of those are targeted as more or less the "allrounders" if someone wants a board with a huge range for all their sails - ideally the 82 should handle weights from approx 75-80kgs/86 from 80-85kg/92 from 85-90+kg etc...generally having a Cpl more litres than your kg weight is quite comfortable, especially on the modern multifin boards which have a much bigger range than older single fin boards...
I'm 78kg and really like the Grip 86 with a 5.3/5.0 gusty winds, but when it's powered up 5.0 I prefer to be on the 82 as an allrounder, especially then when it gets windy. But in the onshore conditions, it's pretty nice to have a bit more volume/often more gusty. and you are heavier, so I guess the 86 could be your board then?