2005 MR Mace Windu Conversion

This may sound like a stupid question and I apologize but I'm following the 05 MR Mace Windu - Done & kits available tutorial to finally convert mine. I'm unsure where to cut the stock housing and the tutorial looks like a picture is missing. I don't want to cut it in the wrong place and have a floppy blade holder! It says to Replace the electronics cover and rear screw. Line the ridge on the new blade holder up with the ridge on the stock housing. Cut the housing where the bottom of the new blade holder is. But where do I make the cut?

I'm leaning toward the position 2 picture. Any help will be appreciated. :D

https://i.ibb.co/DY751KV/2005-MR-Mac...position-1.jpg - Position 1

https://i.ibb.co/809zP94/2005-MR-Mac...position-2.jpg - Position 2

Edit: Thanks for looking but I just went with position 2 and it seems to have worked