Your conformer is probably adding the scaling of the base figure again .
You should be able to simply scale your clothing back to fit the base figure, and when it conforms the scaling should be applied.

The morph can stay in , because its not a clothing morph Poser wont add it again .

Dont go into setup room with the clothing. Just use a donor CR2 and replace the geometry lines (there are two of them) with your clothing geometry