I am trying to make a fiberglass mold from a plastic plug. The plug also has fiberglass in some areas. I have sanded the plug to a shine using 2500 grit sand paper. My question is this an acceptable surface to wax then spray pva on? I am new to all of this so sorry if it's a stupid question. Thanks

It's always better to spend the time getting the plug to a mirror shine, rather than spending time on the mould. If you can get it to a shine without paint then perfect, if not then it's better to paint it than to try and polish a dull mould.