Head Gasket

In an attempt to lower the CR on an engine I'm getting ready to replace the
stock head gasket with a thicker one. I'm also going to replace the head
studs with ARP studs at the same time. I know the stud holes need to be
chamfered (they needed it last time but I did not do it). Any
recommendations on the best was to do this? Should I just use a drill bit
somewhat larger than the hole or do I need some kind of counter sink?

TIA
Larry Miller