Deciding the EV of a bet on the turn

[Nietzsche]

You hold 8[img]/images/graemlins/spade.gif[/img] 7[img]/images/graemlins/spade.gif[/img] on the button. The games is 6 max mid limits. Two limpers in front of you, SB (standard TAG 25/15/2.5) raises, BB folds, limpers call.

Flop comes K[img]/images/graemlins/diamond.gif[/img] J[img]/images/graemlins/spade.gif[/img] 2[img]/images/graemlins/spade.gif[/img]
Preflop raiser bets, limpers fold, you raise, preflop limper calls. 6.5 big bets in the pot.

Turn is 5[img]/images/graemlins/club.gif[/img]

The preflop raiser checks. Now the question is whether to take the free card or to bet. I think betting is often right because you will have a good deal of folding equity but this isn't the point of the post. What I am more interested in is a method for arriving at two numbers: The EV of betting and the EV of checking. How would you go about this? Or are there just too many factors to consider to arrive at two numbers that make sense. Of course precise numbers are impossible, but how about reasonable estimates?

Edit: Just to clarify I am only interested in Limit, not NL