I am trying to create a widget blueprint/tool that moves the pivot for many selected objects

I’ve got a scene with a few thousand actors, all just simple primitives like cubes and cones. What I am trying to do is figure out how to set the pivot to the bottom/center of the Z axis of each object. I’ve got it figured out as far as creating a widget with a button that runs a loop over all the selected objects, but I’m stumped on figuring out where to access and move the pivot. Can anyone help? The pic attached is as far as I’ve made it, I know that will work to loop through the selection, but can I even access the pivot this way?