Howdy,
It sounds like they weren't hurt too badly. I like to use Rem-oil as a rust preventive on my moulds. I wait for them to cool, then spray them and put them away. I would try spraying the affected parts and let them soak, and then try twisting a bronze bore brush in the cavity to loosen any rust inside.. Use a steel brush to clean the vent lines (your moulds might not have them) and to remove any surface rust. The oil will loosen any rust in the screw holes, too.
Lyman sells mould rebuild kits, with new screws and sprue-plates. As long as the cavities and mating surfaces are clean, the exterior doesn't matter. The fact that you can read the mould numbers is good news!
Take your time and let the oil do the work. As far as bullet quality goes, by the time you size and lube the slugs, a matte finish to the nose won't matter very much.
As for the #457401, that appears to be a 193-grain target bullet for the .455 Webley. Same for the Lee 456 mould. They could both be sized down for the .45 Colt, or used as a plinker/small game bullet in the .45-70, too. You are a lucky guy!
Bitterroot