Switching to front disc brake questions

I don’t know why anybody makes a disk brake kit for those 9” drum spindles. I can’t imagine spending that kind of money for a disk upgrade and keeping those 9” drum spindles with their inferior lower ball joint design. There have been failures of those undersized lower ball joint bolts.

Wilwood makes a kit for it. It includes a new spindle, but same ball joints. They also make a nice master cylinder and proportioning valve, etc.