Here is what I blocked the 2 front holes with. I used 1 1/4 x 1/4 inch plate washers with on 3/4 x 1/4 washer in between that fits inside the hole with a nyla nut I used stainless. I would suggest getting the screw with a hex head and actually feeding it from the front as it would be easier and you could use a ratchet and wrench instead of a screw driver lie I did.
