The method majorShrink sent to the Smalltalk object discards certain parts in the .image file to get a smaller image.
The method majorShrink as such does not function properly in a 3.4gamma image. However the code in the method contains still value functioning parts which can be used to build your own shrinking method. (The Smalltalk global variable is an instance of SystemDictionary, so the method you want to look at is SystemDictionary>>majorShrink.)
Here you find some notes how to produces an MVC only image on the base of a 3.4gamma image.
You find a list of removal scripts here. And SystemDictionary discardXYZ methods.