Lower ball joint question.

I don't recall, but I don't think so as regards the mounting surface. Make sure the bolts you use fit tightly inside the new BJ. IIRC, the bolt sizes are different between drum and disk. IIRC,one of those spindles is tapped for the bolt and the other is a thru-bolt, but I don't recall which is which. Also pre-fit your rotor to make sure the exposed bolt-end doesn't interfere with the ribs inside of the hubs

I would not use that BJ until it bolts up properly. If you torque it up the way it is, you will have a massive amount of pressure on a tiny patch of metal adjacent to or around the bolt. After an unspecified amount of time, the soft spindle will get hammered out and the torque will go away. Then the nut may work loose.And that is the beginning of sorrows.
If you loc-tite it, at least it won't come apart, but sooner or later, you will have to retighten it....... over and over, until some sort of equilibrium is reached.