[wmfights]

Reading through the OT, how many unrighteous Israelites did God save?

I'm not sure that's a good way to frame the question. Clearly, there were souls in Abraham's bossom so some people were saved. Also, Hebrews 11 gives us the superstars of the OT and they were saved.

[1000 silverlings]

Well, I'd say God didn't save any that were unrighteous, and by "unrighteous" I propose we used the example of Abraham, who believed God, and it was accounted to him for righteousness.

If you like, use repentance as righteousness, the fear of the Lord and eschewing evil as well. Add to that, keeping the Law.

If God didn't save these unrighteous ones, why not? they were Israelites. Weren't they in the covenants? In fact, time after time, we see great numbers of them destroyed and only a remnant saved.