Making a PU replacement by casting would be far easier and cheaper than modifying the OEM bracket or fabricating a new one to fit the ES bushing.

Is polyurethane mold-injected or cast in a mold when it'* molten? I don't know the properties of polyurethane

Mix and pour.

Oh it is?

The mold, would Plaster of Paris be okay? I know I need to make a reverse mold so that means I need a OEM bushing. I wonder how much the Polyurethane kit is, i can't seem to find a kit online, perhaps I'm using the wrong search terms.