First thing you need to do is take the rotor off....I think you have this one covered (remove dust cap, codder pin, nut, then pull).
I would back off the torsion bars or support the lower control arms firmly with something. When you disconnect these it may have a tendency to unwind the lower control arm which could be dangerous.
Take off the codder pin and castle nut for the upper ball joint and then beat the hell out of the knuckle where the taper is with a hammer. It will separate.
With the rotor off, you'll find two bolts near the bottom. Remove these
When you take those through bolts off, it will be loose at the bottom and you can remove. Make sure you take those bolts and all the spindle nut hardware with you. You don't want the lower ball joints as you'll have to buy them for a 73-76 A-body anyway.