If it's an 8BA with stock heads, I would consider using bolts, like the originals. I even use bolts for aftermarket finned aluminum heads. Most aftermarket head in recent years have been made with oversized bolt holes and tend to fit so loosely that they can actually slide around during installation. Here is one way do solve that problem : https://www.fordbarn.com/threads/more-modifications-to-my-edmunds-8ba-heads.201601/.