Well, the issue you'll have there is hammer and dollying, bending that lip because of the curve to it. Not so much what you do with the slitted lip after, but getting the radius to the bend.
You would be better off just cutting it clean to the lip you want. Then welding another piece for the lip.. That way you can curve the lip to match the curve of the fender..
Years ago we used to get these patch strips for rust repair, I'm racking my brain trying to remember what they are called. They are basically just a piece of angle sheetmetal, about an inch on each side, with slits cut all the way up it on one side. They would be real easy to use in that way.. trim the slitted side short to fit behind the fender lip, bend piece to fit, clamp in place, mark tab locations, remove and drill holes or use a flange/punch tool on fender lip, reclamp, poormans spotweld it on, then mig the edge..
Personally, I think the easiest, best way for the average joe to do it is the, bend a rod to fit the edge and weld in place idea..
When I do mine, I actually plan to resection in my cutoff lip higher up, adding the patch piece in the middle to fill the dimension you lose... iirc, that is the method also used by someone on here with a first gen. Might have been VTblazer (?), the dude starting his own first gen bodyshop... maybe he'll chime in..
