Brake Info Needed

[pjdeb]

It is my first time taking 1930 A brakes off. First of all, Henry could have put a little more meat on the backing plat bolts. Struggle to get them off as they spin. Anyone put a slot in the head? Changed to a bolt with a larger or different shape head?

Can anyone tell me anything after looking at these pictures? There seems to be plenty of thickness, but surface seem vary glazed over.

Any comments appreciated as I am new to this.