Front suspension swap help needed

I am curious about this too. I have a front sway bar with the calipers mounted on the front and do not have any issues.

Its possible/doable. Some aftermarket front bars attach at lower shock bolt and/or have different bends and may not conflict with forward mounted late model calipers.
The OEM front bar has very long end links that loaded above a tang this is very near the lower ball joint. Late model calipers will hit that set up if the calipers are mounted to front. Convention solution was to switch spindles left and right so the caliper mounts to the rear, away from the sway bar. Longer fluid hoses are required.
In recent years people have figured out to use the shorter late model end links loaded beneath the attach tangs. Moves end links and bar below the front mounted caliper. No conflict.

Do the 67 and 76 lower control arms use the same size ball joint?
Yes. You must use the correct lower ball joints for their shape, bolt to spindle configuration, but the ball studs to lower arm are the same size.