I usually remove the rocker arms and pushrods, bolt a couple of pieces of angle iron to the head using two rocker stand bolt holes, with 3/8-16 Grade 5 bolts, and attach a piece of chain to the angle iron with clevises. That gives a straight up lift to the bolt instead of a sideways shear force.

"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!