with a 2.5bb,3/4 spacer in the front, and a 1 inch body lift would that stretch the brake lines???

 

You'll be getting close on the brake lines, but you should still be OK with that setup. The best way to make sure is to use a jack and put each of your axles at a full droop situation. Some kits also have you relocate the hard lines, so if it is close that may be an option for you as well.

 

you'll be fine up front but in the rear, you might want to install a set of drop brackets.