Well, used metal isn't common anymore, but my guestimate is based more on time than the readily available reproduction materials.
Just finished my '67 S which was extremely solid, but the metal work time was not insubstantial... this poor car will need everything.
Like Eric, I once got a '68 S Targa cheap, it too had sat in mud. Not as bad as this one but pretty frightening to me: you could poke your finger through the rear torsion tube supports.
Car flipped to Europe at a profit where it was restored with "G" slam panel, driver's B pillar and god knows what else. Rare though, not many '68 S Sporto Targas.
Don't know if it sold yet or not but the asking price was ridiculous considering what they went to work with. Oh yeah, a manufactured "California history" was included along with "numbers macthing" 901 tranny...