Bottom line, you should be able to write up some simple wrapper functions using the above references, that you can then expose to Blueprint for you to use anywhere in your project.
Follow-up: you may also want to read this article, which explains the troubling limitations of the (FString to Int) Atoi function. In short, you can’t always trust the output of that function, and, depending on your usage, you might be better off not attempting to convert strings to integers at all.
You can use two methods, a split or a parse. A split works fine when you know for a fact it never changes from “ClassName_#”. I recommend a parse, as it will work on everything from “ClassName_#” to “ClassName_Child_Instance-test_#”. You get 0 for “ClassName”. Works without fail. Enjoy.
I believe @Dank22x doesn’t want to set anything manually, otherwise there would be better ways to reach the goal than converting the display name into int.
But if the name always starts with Box_, the “Right Chop” node with Count 4 can be used, no matter how many digits follow it.