With the conveyor in the machine have someone push on the conveyor to create a gap between the conveyor and the casting.
Insert wing brackets  between the top of the conveyor and the casting. make sure the shoulder of the mating bracket is against the wing brackets.
With the brackets in place install self tapping screws at the TOP of the slots in the brackets. This will allow you to bring the brackets upward to meet the casting if necessary.
NOTE: Make sure the bracket is wedged between the casting and conveyor to create a seal so chips do not leak through the gaps.