How's the compression? If that and the ignition timing are within spec, then
the carburetor shouldn't have to be set rich to make it run smoothly.

That's a fact of life on older cars.  Many years ago I bought a used 240
Turbo, and it started and ran perfectly when cold.  I did a tune up,
changing all the normal tune up parts, as well as setting the slightly
too rich mixture back to spec.  The next morning the car started, and
immediately stalled, I restarted 3 times before I could keep it
running.  I though about what had changed - and move the idle adjustment
screw back to where it was - and the problem was gone.  And this is with
fuel injection - carbs are more prone to these problems.  My friend that
runs the Volvo garage tells me that setting the old B21As to spec is a
sure way to make the customer mad at you - he sets them all just rich
enough so there's no running problems.  He always keeps them overnight
so he can make one cold start himself to make sure he's got it right.

I would suggest you raise your opinion of your mechanic at least back to
where it was, maybe even a tiny bit higher.