I came into possession of a similar conditon gun in 1974 in Florida that had been buried in 1968. I used muriatic acid to clean it up, replaced all the springs (which had rusted away), the grips (which rotted away), the magazine (also partially gone) and one grip screw that had been partially eaten away.
The gun was a 1952 commercial production, and still had a legible serial number which was reported to Metro-Dade. It came back "clean," although we always suspected it had been used in a crime due to its former owner and the circumstances of its "burial."
Anyway, after the acid treatment, new springs, grips and a magazine, the gun shot fine and has been in constant use ever since with no problems. As an extra bonus, despite the pitting in the barrel, it is reasonably accurate.
What is amusing is the fact that, from a distance, the gun looks like it has extensive engraving all over it.