If Greedo gets killed by a jet trooper using overrun, so that his space is occupied by another figure when he would make his parting shot, are there any restrictions on if/who he can attack in that case? I don't think there would be because he's not ending his movement in another figure's space, he was already there. just wanted to make sure.

The target must be in line of sight, the target must be a hostile figure or object that can be attacked.

(Greedo has ended movement during his activation, and suffering damage does not cause him to start moving.)