Front Suspension Height Adjustment after 1971 Front Drum Upgrade to 1973+ Front Disc Brakes

Have to disagree with Murray. That method may visually level the car, but it won't align the front end or equalize the loading on the wheels.

I think you are right that the 73+ spec applies. The larger ball joint would increase the height difference between the blade and the ball joint. Try it and see if it looks plausible. You probably will need an alignment to set caster and camber after you set the ride height.