fullsize chevy notch install

I am about to weld in a notch in my buddies 97 full-size Chevy and was wondering if most people make the notches parallel or continue to follow the frame? If you do make them parallel is there any trick that helps make it easier? The notch I'm installing is the suicide doors bridge and notch kit that has a tubular straight bar bridge. The reason I ask is the frame angles in which I'm used to the s-10s with a parallel frame. Thanks for the help.