The Hughes studs I bought years ago were noticeably shorter than the ARPs I use. I suppose you could put a small amount of locking compound on the threads, but don't overdo it. Haven't found mine loose during tear-down, but they do unscrew pretty easily once the nuts are backed off.

No way in He11 I'll use bolts to hold down the rocker shafts w/ aluminum heads. IMO, that's just asking to pull the threads outta the heads when tightening the shafts down.