There is a solution to the over rich mixture that the Weber puts out. 
 Firstly the mixture is purposely jetted over rich for a reason.  
Since the intake manifold runners are so long a lot of the atomized 
fuel droplets cling to the manifold walls.  This means that at idle 
or slow speeds the airbourne mixture is a lot leaner than the total 
amount going into the cylinders.  Raw fuel drips down the manifolds 
and irratically hits the cylinders giving a pretty rough idle as 
cylinders randomly get raw gas or the leaner airbourne mixture.  
Instead of re jetting the carb just put a calibrated airbleed in the 
intake manifold.  A little valve screwed into the intake manifold 
that is opened up to the point where the mix is dead lean 
(assumuing that it is set normally if completely closed) for the 
test should give you a very low HC reading.  Once the test is over 
you can just close the airbleed valve and drive normally until the 
next test.  Normally I set my weber up by ear but you can play 
with the bleed and increase the idle speed to get the HC values 
down.  

What numbers did they report by the way?

Bye for now

Andy