When I use a drop-down menu, I like to see the selection I made from the list before I go on. Sometimes I could get the one above or below the selection I actually want. So, if I were doing your particular example, I would want to make the selection, see it, then click a go button to get the desired results. It may be easier than getting results which are incorrect and having to come back to the drop down menu and start over again.
I suspect you know the script to do it would be Enter Find Mode, Set Field, and Perform Find.