CBR600F4i / CB900F Throttle Body Adapter - Initial Design

So I've been working hard to create a CNC prototype for my throttle body adapter.  The initial idea was to create a 2 piece design that will bolt to the TBs.   I have a 3D printer handy, so I am able to print out the design for fitting.  I will be using LibreCad for the 2D design and then extruding it with OpenScad.  Both are free open source tools!  The baseplate and airbox connector look like this...

After considering that I will have this CNC by a shop, why not just make a 1 piece design?  It quick evolved to something like this...

Initial test fitting.  The o-ring looks nice and snug.  And it fits the TB like a GLOVE.  This is not very good since I have to consider tolerances of the OEM TBs.  They are mostly casted aluminum.  Judging by their OEM plastic airbox, I will need to provide more tolerance.