As for "drop in" parts...Nothing is really "drop in" is it? I'm going to have to buy a few things.
A beaver tail, flat mainspring housing, night sights, grips (10-8 performance, love them), bigger ambi safety, combat trigger, skeletonized hammer......then!
Finish......I'm thinking bluing? Guys? Help me out on the finish? Not stainless....the Gold Cup is stainless and thinking about carrying it pains me.
Some parts my require minor fitting, but what I meant by "drop in" parts is that the gun itself wasn't irreversibly modified to work with the new parts that were added.
As far as finish goes, your gun is made from carbon steel and finished in satin nickle. It can't be re-finished in stainless, as stainless is actually a type of metal that is usually polished and then left without a finish, like your Gold Cup. Since it's carbon steel you have a lot of different finish options available, you just need to pick one that's appropriate for what you intend to use the gun for.