to select big area face among faces and move

I need some help, so I will post again

I have the following code

This only selects the faces that are visible on the screen.

From here
I want to reselect only the face of the largest size

Then detach it
I want to move about 200 in the opposite direction to normal

What should I do?

theTM = inverse (viewport.getTM())

for theObj in Geometry where classof theObj.baseobject == Editable_Poly do
(
theFacesToSelect = #{} --ini. a bitArray to collect faces to select
numFaces = polyOp.getNumFaces theObj --get the number of polygons in the EPoly

for f = 1 to numFaces do
theFacesToSelect[f] = (in coordsys theTM polyOp.getFaceNormal theObj f).z > 0

polyOp.setFaceSelection theObj theFacesToSelect
)

redrawViews()