I have to change the front part of the passenger front fender as it was rotten around the bucket which in turn led to rotting at the bottom.

I have discovered bondo hiding damage on the other side so can't rely on that for measurements.

My car is a 74 with black bumpers with the 2 rubber bumper stops on the front. The arches are also standard narrow width.

Can someone tell me what the correct gap size should be on the side between the edge of the bumper and the ridge of fender?