I like to use a 1/2"-13 bolt about an inch longer than a head bolt to secure a piece of angle iron to the top of the head in a couple of places, then use a clevis to attach the chain to the angle iron. I don't trust losing a lot of thread engagement on the head bolt as it goes through a chain link.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!