Err ,Plater Josh is the bloke you need for good plating.And he plates potmetal / diecast / ****metal .
if the chrome shop is good they will know just how long to let the parts sit in the copper to make it smooth. spending your own time on prepping the parts BEFORE they chrome them will be a huge help! once you have the parts smooth and i mean FILE and sanding block smooth, you can send it to them where they put the parts in copper and polish them to a smooth finish, and then they nickle plate(i think in that order) them, and then chrome it.