remanufactured calipers don't seem to have all parts

[triacon]

looking at either rebuilding my front calipers for a 1985 300sd or buying rebuilt ones at a local store. see attached link http://www.napaonline.com/Search/Detail.aspx?A=SDC24271454_0230527224&An=599001+101985+50044+2044068#

this does not have the heat shield, at least not in the photo's. My questions are, do I need the heat shields and shims for proper brake control?

What do those parts actually do? are they redundant?

I pulled out the inner piston on the right front caliper. It has a few spots of pitted corrosion on it. I rubbed it over with a brass brush. It got some rusty stuff off the piston but when cleaning off all the mess, I saw the finish was missing in some tiny areas... The outer segment of the bore is also rusty so I am not sure if it is worth rebuilding or just get a rebuilt set and send these in for the core return...