By the looks of it you are in need of a new cover. The cast of that cover has a female nipple that comes out of that location and the pulley bolts to that nipple so the nipple portion is concealed by the roller. You are also missing a bracket that is attached to the belt tensioner too. My guess is that whoever had this before you put a threaded stud in there in place of the cast nipple and that is why the washers are there so he or she could sale the vehicle. And for someone to do that tells me that they had some sort of aftermarket parts on there before you bought it or was just a junkyard mechanic and tried something that his grandpappy showed him years ago, you know the theory, zip ties and duct tape fixes anything theory. You might want to try and take a washer or two out and see if the roller still clears the cover. If so, that may buy you some time so to get a proper cover and attach that roller properly.
Did the previous owner have a different setup on the engine to want him to cut that nipple off that you know of? How much a used one from a junkyard is I do not know. How much a mechanis would charge you to do the job, same answer. But either way, your setup as it is is wrong and needs to be fixed.