A little advise from someone who had to have the pot metal done at the time because no repro parts where available. Lots of work goes into getting pot metal to maintain it's size. If you grind off the metal to get a smooth surface, then the shape is not the same. If YOU pay to have it dipped in cooper several times and sanded down then dipped again and again, what would you think the charge will be.
The door handles on the Roadster are pot metal and were in excess of $100 for each and they are not perfect.
Moss and others sale a complete set of handles, glove box and trunk opener with keys for $175, unless you are a purest or have lots of money to throw away, just get the repo ones. They look nice and are much nicer than you would except.
Now if you are lucky you might fine some on Ebay that are not pitted for chroming.
Wayne