what course of action is indicated?

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   I brought the Jav to a dyno shop (chassis dyno) to check on the engine's performance.The result is that the A/F ratio is quite rich (401 w/crossram and Holley 4160s,
mech. secondaries) and needs to be leaned out.  Primary jets were already replaced
by a smaller size to have a leaner idle, as the initial idle was too rich.

My mechanical engineer friend says that the first thing to do is to enlarge
the main/high speed air bleeds to introduce more air into the system. Then,
he says, I can change the secondary metering plates to a smaller "jet" opening.
He feels that a valve might be burned in the process of dyno-ing the engine if I don't
modify the air bleeds first.

The dyno shop and another carb buddy say no, first thing to do is to change the plates
and that any main/high speed air bleed changes will be inconsequential compared
to the plate changes.

Which direction is "more correct?"  Is there a more effective direction to take here?

See graph below.