For a Belgian Blond, I'm sure Belgian pilsner is preferred but I'm sure the domestic pilsner will be fine. It might not have as strong of a malt flavor. I would just add a bit more aromatic, it will help with the malt flavor and keep the color correct. I would also eliminate or lower the amount of sugar and use more Pilsner malt, which will increase flavor as well. Just mash real low like 148 to keep it dry.