SuperStock spring tips.

I think you have plenty of angle of the rear shackles. There isn't a specific number. Don't worry about getting any more. I used 3/4" spacers with no lowering blocks on my car and doubt I have that much.

The idea is to have enough angle so the bottom part of the shackle doesn't run out of forward "swing" when the body rises. But I don't believe in excessive body rise anyway.