340-S Hood inserts who "restores" them ?

This is something I have contemplated for a somewhat long time. Die cast pot metal (everything that gets thrown into the pot, zinc, aluminum, lead and other heavy metal tag alongs) is expensive to restore. The bubbling and blistering you see is not from weathering and neglect but from impurities in the metal itself. That happens from the inside eventually to the surface so no diecast part or restoration for that matter will last forever. Each blister must be dug out with a carbide burr to get all impurities out and filled with welding rod with out distorting the casting, then hand shaped and smoothed for chrome plating. Muggy weld makes welding rods, google them. But before you diy, realize that no chrome plater I know will plate diy diecast, they use professional service they can trust cause of how their chrome plating going to look in the end.

I have contemplated duplicating diecast in aluminum billet (not cheap either) and having it plated.

if you still want to have diecast restored, you can find vendors in Hemings motor news or old cars magazine.