37 Ford build--IE: old Header issues thread /37 Ford/5.0/GT40P heads

[randyr]

So here's a new question for you guys: I bought one of the gas cap kits as shown in the pics. I've seen installations where a rectangular hole is cut in the fender and the whole unit is welded in. Since the curvature doesn't exactly match my fender, I thought it might be easier to fit the lid to the existing hole in my fender, then remove the sheetmetal from the top of the box and weld the rest of the unit under my fender. If I do that, what's the best way to trim out the whole in my fender so it's the perfect size?