Of the range you give villain when he raises the flop (I'm not sure J7-J8o would be in his range preflop, but otherwise, it sounds pretty reasonable to me), what do you think he would fold to a 3bet? Stuff like 99-TT, QJ, non-spade 65? So against his continuing range you'd be at something like this?

Board: 8s 7s Jc
Dead:

equity win tie pots won pots tied
Hand 0: 46.336% 46.01% 00.33% 32794 234.50 { QsJs }
Hand 1: 53.664% 53.33% 00.33% 38017 234.50 { JJ+, 88-77, AsKs, AJs, KJs, JTs, J8s, T9s, 98s, 87s, 6s5s, AJo, KJo, T9o, 87o }

With fold equity and the chance villain could be spazzing, this seems like it could be a profitable semi-bluff, right? (I actually kind of suck at 3betting, so I am running through this thought process for my own good too.)