Need help sinking a windshield

Hi all, I either want to sink my windshield and chop the roof or cut the windshield and chop the roof. Which one would be easier? It is for a 62 chevy truck with a wrap-around windshield. Can someone explain to me if i sink the windshield into the cowl where do i make my cuts on the metal below the gl***? I never did this before so i need all the advice i can thanks.

 

Seems like the long way around the barn doesn't it?