How to fin it mostly comes down to how you want to surf it.
If you want it to surf it more critically, like a HP longboard and from the tail, run it with the bigger 105 sides and 83 centre. Although at your weight those side fins are most likely too big and stiff - unless you really like the push it would give back. I do reckon you'd love it with quobba large sides and med centre (or all mediums). Bert likes using a smaller rear to loosen up the tail on his Hp longboards. I prefer it on my custom LB too.
If you want to use it more like an all-rounder, using more of the board, eg. from the middle - a 7-8" centre and maybe some 3.5-4" sides would be sweet. Shapers fins offer plenty of options.
I'd also try it with a big single. 9.5-10" - neutral fin. When u want lots of flow and style. It isn't a nose rider per-se but could still be ridden that way - it'd super fun on smaller days. The paddling benefit of only using a single fin shouldn't be sneezed at either.
In any way you fin it, you've scored a sweet ride that will be very versatile and a keeper I reckon.
I could ride it as a prone board haha