That's how I found the center. Cutting works even better if you have a plasma cutter and circle cutting jig. We welded a piece of rolled 3/8" round bar to the diameter of the "hole" to stiffen it up some and maybe shield a little of the water from getting in. You gotta work fast here, I just noticed there's only 2 wks difference in these two pic dates and look at all the rust...
Well now you know how to find the center. And it looks like you wont be making a round hole. So I'd measure a couple times and make your first cut a little on the small side of the shape you are going for. Then test and measure again and trin to fit. I used to have a chrome scoop sitcking through my hood when i was in high school and the car was primer. I love the way it looked. I used some stick on chrome door jamb trim on the edge of the hole, you can get it in black too.
yeah...the article is going to help alot @ryan: i think ive seen that trim at autozone before, but i havnt seen it in black