Aksel Pedersen asked for some dimensions of the new flanges so I figured I'd make a post for others interested as well.

The rigid flange base is 3-1/8" x 3-1/8" and has a 2" by 2" bolt pattern.

The adjustable flange base is 2.75" x 2.75". See the last photo for the bolt pattern/dimensions.

Let me know if anyone has any other questions!