You have a 73 fender on the DS and a 71-72 fender on the PS
Don't even try to weld up a piece, I had a good 71-72 fender for my 73 and though it could be done however the notch on the fender is different as well as the inner sheet metal, so I never tried to modify the fender because I would not have been happy with the hodgepodge.
I just ended up swapped a guy for my 71-72 for a nice 73
I am just at the point of fitting the fender , bumper extensions, fender extensions, light boxes and must say that I am glad I have the proper fender as there is to much going on in the front corner to mess with
Good luck