The front 105E bumper has 4 square holes for chrome bumper bolts. 2 would be sufficient. It is very light.
The rear Cortina bumper has the 4 square bumper bolts, plus 2 round bolt holes for fixing the Cortina number plate. Just 2 square holes for the bumper bolts would be sufficient.
The less holes, the less perforations, the less bolts, the less the bolt costs, the lighter the car is, and the less likely there is anything to rust.
Chunky would approve.