On the dizzy, if you look hard, it's stamped with the model number (25D, 45D, etc) along with some other numbers.
I'd set it for what Haynes says if you got regular plugs... A few of the weird design plugs are preset to optimum for the plug (bosch +4, for example).
The Autozone guy's no squat about old car engines. .024 is probably for some new honda - whatever...