Advice for drilling on my intake wanted.

Standard black oxide drill bits from Home DePot or Lowe’s... drill slowly, not high speed.
Thanks, should there be any play at all or do I want that drilled out only as wide as necessary to receive that bolt? I don’t know if any play is required at that spot once the intake and exhaust are sandwiched together for flex as they heat and cool. I know that they flex and slide across the face of the head as they heat and cool but wasn’t sure bout movement at this bolt spot.