Bill,
On my 70 SSConv. I did the following to fix some rust.
1) Remove the windshield, best done by your friendly neighborhood glass shop.
2) Clean sealer residue off of windshield frame by using a putty knife and finishing with some mineral spirits and rags.
3)Thoroughly wirebrush the rust spots.
4) Brush paint the rust spots with POR15 paint. (This stuff must coat only bare metal or rust, not paint)
5) Use POR15 2 part putty to fix any holes or craters. Sand smooth when dry.
6) Prime POR15 surface with their surface primer you can also prime old paint areas.
7) Paint with body color or semi gloss black as appropriate.
8) Have glass shop re-install windshield.
Good Luck!
--Andy--