Been working on my left rear fender for a while, welding replacement metal in small pieces to maintain curves and shape. Just finished the twenty or so patches (yes it was badly rusted) on the left rear fender and attempted to fit it to my 63 RutsZilla.

To my surprise it does not fit well. Although the body is in bad shape and has some holes, the body lines seem to be straight, but it has quite a bit of body filler. I have a larger than required gap at the top rear of the fender and the front section which supports the stone guard also has gaps.

I started replacing rusted out metal on the left rear quarter panel in the hope of finalizing its shape. Then perhaps I can beet the fender metal into shape or just fill in the gaps with more metal to improve fitment. I suppose I could purchase new fenders, but they are quite pricy and used ones are rare and maybe also in sad condition.

So, are there any experienced metal workers on the forum who care to share techniques? I was cooling the metal with compressed air as I was welding, but it did not seem to help.