You'd have to drill out both the spindle and the lower ball joints. The lower ball joints having enough meat would depend on the casting and how well the holes are centered in it, the castings vary some by manufacturer and by year (new manufacture vs NOS), and I have definitely seen some that didn't have a whole lot of extra material around the mounting holes.
The spindles are a lot more accurate and they redesigned the spindle when larger bolts were used to keep the strength the same (or better). Typically spindles have a pretty robust safety factor built in, but you'd be trading strength at the spindle for strength in the bolt any way you look at it.