kirkoff

I was removing my power steering control valve on my 1968 coupe. I could not locate the roll pin. I think it was sheered off by a previous owner. I have read to re-drill a new hole for a pin but have no idea how to do this. Do i need a special tool to drill into the round steel? Can I just screw on the new valve and use that as a guide to drill? Any and all help appreciated.