Replace the crappy Glock sites with your favorite aftermarket ones.
How much trigger time do you have with the Glock action?
If you don't have a lot of experience shooting a Glock, I would recommend keeping it as-is upon return from refinishing. Instead of modding it, get a lot of practice "riding the sear" during both slow and rapid fire practice. The Glock trigger is an interesting animal, one of it's primary advantages is the short reset relative to other DA action types.
Since you are an experienced shooter you should be able to master this technique quickly. Once you do, you may not want to perform any mods that decrease the pull-weight of the trigger. From your post I get the impression that this gun is supposed fit the role of a practical CCW/ combat handgun that you also compete with informally, right? If so, I would stay away from lighter springs and metal guide rods, they have a reputation for decreased reliability with little improvement in practical performance.
I don't currently compete in any "gun games", my G19 is for social situations and my primary concerns are reliability and combat accuracy, hence your needs may differ from mine.
