I must disagree with starting with the hood.

Start with the door to quarter and rocker, those are fixed and not going to move. Finish with the hood and fender gaps, they are last in line. The gaps at the cowl are the last of concern, you want the fender/door/quarter to fit nicely next to each other when looking down the body. You see that from far away, cowl gap not so much.

On a b-body the fenders bolt to the inner fenders and there is no side to side adjustment without bending metal someplace. If the car was never hit hard they usually fit fine side to side.

If you are installing flooring do you start in the center of the room? Or at the edge?