My new 71 Demon project

Well, the 110 degree weather has broke, and just back from the Nats with a fresh dose of motivation. So now I'm ready to start some sheet metal work and tackle the worst part of it first. Swapping out the cowl. I'm hoping to get some advice on the best way to go about it. I've attached some pics to show what I'm up against. I was thinking about going at the spot welds along the seam in the firewall and the window channel. But not sure how to go about the ends and the a-pillars. Any help would be GREATLY appreciated.