Standard 3bet flop line

[Terkman]

6max 25/50 online game on smaller site. Game is playing a bit more passive than at FTP. For several reasons that I don't want to tell haven't I 3bet as much as usual.

Utg+1 pots, folded to me in SB, I 3bet with KK. HU to flop of 987r. Effective stacks 6300. Opponent is solid winning regular multytabler who I assume is capable of moves but seems pretty tight and abc. No history with opponent and no other info on him. Whats my line?