Well according to my Snap On tap guide if you're using a 7/16-14 thread wich is what the studs in Jegs calls for you should be able to tap them right out,just be carefull,take your time and use plenty of lubricant,there's some really killer stuff out there called Tap Magic and it is but it is also expensive,you should use a starter tap to start the threads and finish with a bottom tap as you're dealing with a blind hole,you'll probably be way ahead of the game if you clean the oil off the top of your heads and tape off the valve springs and the pushrod holes so all you have exposed is just the row of stud bosses that way you can lube em & tap em and blow the holes out with compressed air,I don't know what the stud kit will call for but you might want to use some Red stud set lock tight on your studs so the holes and the studs will need to be clean and dry,that's all I can think of now,use some good sticky duct tape and maybe get your hands on some masking paper? That ought to keep the shavings out of your engine!!
Good Luck!!
Good Luck!!