Studs are great if there's clearance to get the headers on and off, there usaully isn't.

The next best choice like what was mentioned is 12 point header bolts that are long enough. A lot of header bolts I have seen are too short, I don't know why, maybe for cheaper,thinner headers?

Reg hex head bolts won't work most of the time.

A auto part store that sell's Dorman can get you the correct size studs, you need to know what size you need though.