Overscan rendering in Maya 2017 and Nuke 10

Need to do a overscan a shot to make sure there is enough room for soft ground shadow. Scenario:

Project original output resolution is 2048x1366. All the rotopaint nodes have set up to work with original resolution. Decided to do a x1.4 overscan while maintaining the original framing of the shot.

step 1)

Change Post Scale in the render camera's Film Back to 1/1.4=0.714

step 2)

In Render Settings, set the resolution as follows.

Width: 2048x1.4=2867

Height: 1366x1.4=1912

step 3)

After rendering the output from 3D, in Nuke, set all your previous rotopaint nodes based on the settings below.

a) in the Transform tab, keep the center intact.

b) set translate x to (2867-2048)/2=409; set translate y to (1912-1366)/2=273

note: you can shift-select multiple Bezier shapes or brush strokes in a rotopaint node to set values at once.