Hi Denny,
I did some magAL stuff that had light pitting.
but havent done pot metal yet
polish
dip in zincate solution
flash copper plating
very thick acid copper plating to fill in voids/pits
sand/polish
copy chrome plate
those castings are usually porous as hell and made of nasty quality metal so im not sure how long results would last
for pot metal heres some info that may be useful
pot metal plating sounds like a lot of hard work! id go the repro part route if thats possible only if its not would I attempt pot metal plating i think