I looked into reproducing these early die castings using investment casting by having the part read into a computer; then making some corrections ( to remove the cracks and ajust for the swelling ) via the computer then 3D printing the part in wax.
From the little I know, the zinc (pot metal) metal is alloyed with lead and this causes internal granular disintegration (ie crystallization). The lead is alloyed to act as a lubricant in the die casting.
By the way; my Lincoln is a driver not a show car. Future owners can do repairs/restoration of various parts; however, preservation, HPOF, is what I have been basing my ownership on.
The technology is extant to read in and reproduce sand castings. Check out ProMetal RTC and view their 3D sand printing machine in action. Repro blocks could be produced for less than 12K.