NLCASH - 3bet or call?

[Rakshasa]

So, this player is unknown and its about 10-15 hands into the game, nothing special has happened so far basically we've been raising OTB and the other has folded a couple of times.

Full Tilt Poker - No Limit Hold'em Cash Game - $0.50/$1 Blinds - 2 Players - (LegoPoker HH Converter)

BB: $100.00
Hero (SB): $100.00

Preflop: Hero is dealt 8 7[img]/images/graemlins/spade.gif[/img] (2 Players)
<font color="red">Hero raises to $3.00</font>, BB calls $2.00

Flop: ($6) 6[img]/images/graemlins/heart.gif[/img] 5[img]/images/graemlins/heart.gif[/img] 4 (2 Players)
BB checks, <font color="red">Hero bets $4.00</font>, <font color="red">BB raises to $13.00</font>

On a rainbow board I think this is a pretty good spot for a call but I'm not sure here. I think a decent amount of his range here is total air/overcards. So many ugly turn cards to come though if he actually has a decent hand.
If I 3bet him here my hand will def look like an overpair dont you agree? So whats the best move vs his range?