<VV> Leaning Out the Midrange

[Mikeamauro at aol.com]

I've installed Ray Sedman's F/A O2 sensor readout system on my 67 110  coupe. 
Readings obtained indicate the F/A mixture is consistently rich  
(11-to-12-to-1) in the cruising range. I've gone as lean as I dare with the main  jets 
(.049s), but jetting does not appear to significantly affect midrange  mixture. 
The purpose of my work is to improve fuel economy (and yes, all is  
well--mechanically--with the engine). My next step is to purchase a broadband  F/A 
diagnostics device (likely with additional RPM input) and begin  experimenting with 
the internal working of the carbs in an effort to lean out  the midrange. 
QUESTION: has anyone out there already ventured down this path?  What area in the 
stock carbs is the most likely place to start in working on the  midrange F/A 
mixture?
Thanks in advance for any information provided. 
 
Mike Mauro
67 110 PG Coupe, with Factory Air