Yes - like that one.
Guess you will have to contemplate what sort of finished effect you want to end up with and whether the guard will stay together - I noticed pin holing on the guard next to the joint with the valence - but as long as the rust moths keep holding hands it should stay together. If it were me I would probably put the "as built" shape front guard on and maybe see if I could distress a new smooth one a bit after painting with wire wool and a brillo pad plus a bit of "weathering" over winter. (i'd draw the line at battering a new guard with a bit of chain tho'
As Johnny has said above its all part of the history - so you putting the new guard on it would also be its history, after a year or two it would tone down, or keeping the existing guard you have ditto - are there any witness marks so can you tell if the existing guard was used on the bike during it's life,rather than just been added to the basket to make it look more complete.