Almost there! I´ve reproduced the flapper mechanisme and vacuum controled valves myself although my friend Mike (from the RAII convertible) provided me with detail pictures from his RAIII setup.
Without these I would not have been able to reproduce it myself!
Maybe that "hole in the market" ?
He even had an handmade version of the flappercase which I changed and modified further to make it close to perfect!
Here are your options: