river bluff vs "good TAG"

[matrix]

Party Poker, $0.25/$0.50 NL Hold'em Cash Game, 5 Players
LeggoPoker Hand History Converter

BTN: $50.32
SB: $166.18
Hero (BB): $47.63
UTG: $88.88
CO: $64.84

Pre-Flop: 4[img]/images/graemlins/spade.gif[/img] 6[img]/images/graemlins/spade.gif[/img] dealt to Hero (BB)
3 folds, <font color="red">SB raises to $1</font>, Hero calls $0.50

Flop: ($2) 3[img]/images/graemlins/club.gif[/img] J[img]/images/graemlins/diamond.gif[/img] A[img]/images/graemlins/diamond.gif[/img] (2 Players)
<font color="red">SB bets $2</font>, <font color="red">Hero raises to $6</font>, SB calls $4

Turn: ($14) K[img]/images/graemlins/club.gif[/img] (2 Players)
SB checks, Hero checks

River: ($14) A[img]/images/graemlins/spade.gif[/img] (2 Players)
SB checks, <font color="red">Hero bets $8</font>

One of the holes I have found in my game is a general lack of river aggression - so aside from trying to make more value bets I am also trying to slip in a bluff here and there vs opponents who might be able to lay a pair down.

Villain is solid looking TAG player.

Hero has played like a bit of a nit this session.

What range (apart from Ax obv) calls my river bet? and is sizing good?

I was planning a bluff raise here on a [img]/images/graemlins/diamond.gif[/img] river if my turn check induces a bet - is that a good plan?

I always gave up in spots like this after my flop c/r got called and shut up shop - which feels really weak.