PCG: Any way to alter preauthored actors after a pcg graph?

[Just found out about creating posts as questions instead of threads so they can be marked as answered]

Hi, all! Should I be expecting to be able to write values to multiple pre-authored actors during a PCG?

For example, say I have placed and tweaked properties on some instances of an actor in the level. At author-time, I just have them at Z=0.
When I run my PCG graph, I want them to take their position, project it onto the terrain, and then move to that new location. Is that possible and/or practical?

Basically, rather than spawning new actors, I was hoping to somehow pipe the new project location values to their respective actors.