I am going to grind off the old suspension point on the bottom of the diff for the rear shocks and make up stronger/longer ones(so the shocks do not hit the diff and damage them).

Question is if I make the bracket shorter(the length it hands down from the diff) does that give me more or less travel when flexing across.
Hope I am making sense?

Are you using longer shocks? With the Calmini kit the lower shock bracket should be ground back to give clearance for the shock. I would have thought it would be easier/simpler to move the top mounting rearwards a little to get clearance. Moving the mounting up should give a little more drop but you may have to lower the bumpstops to prevent the shock bottoming out.