[jt1]

against just 3 opponents and one of them has already checked, I think this is a pretty standard flop lead.

On the turn, you should give yourself 3 overcard outs and 4 to the straight. Reverse domination is a concern as you'll loose one bb if you hit a tainted out and wont gain more than one bb if you hit any of your live outs. But you have more live outs than tainted ones so this seems like a +ev call.