I'm to light... My guess is that 6.0 is a little bit of a stretch on the Q81 (maybe with a convertible with a 2+1 setup and something like a 17-20cm central fins would do the trick). ON the other hand the PA86 is just a smidgen wider and much narrower in the tail so if that one has served you well, probably a Q81 will too.
But I will ask Scotty to comment. He's your weight. It may take some time since he's competing in Reunion at the moment.