Tap out a hole

["Joseph M. Shaw, II" <MikeIIDC@domain.elided>]

Digesters-

I need to know what exactly is the right situation in which to rethread
a hole.  If you guys remember, when I first was getting my '73 Scout II
running a while back, I rebuilt the carb and one of the holes stripped
almost instantly.  I threw the thing together anyway, and it held up for
a while.  It now, however, appears to be pouring some extra gas straight
into the intake, which I assume is from this lack of compete tightness. 
I have tried adjusting everything possible externally (it's a 2210
Holley), though I will take off the accelerator pump arm and the
reservoir cover and look closer today, hopefully.
What I need to know is this:  Would this be a safe instance to try to
re-thread this hole?  This metal seemed really soft stripping out-will
it hold a new thread?  Are the holes and walls too perfectly spaced and
tapping out may cause some trouble?
I noticed this because my mileage went down to approximately 5 MPG (from
about 12), my exhaust turned VERY dark very quickly, leaving marks on
the pavement where I start it up, and I could smell gas-even over the CO
that my Scout sprays on me constantly anyway.  And I can see a little
wetness on the outside of the reservoir-which makes me think it may be a
problem here, but if I'm going to take it apart, I might as well fix the
threadless hole, too.  The wetness is not visible coming from the top,
though, and it does appear wetter down on the edges of the gasket
between carb and intake manifold.
Any input?
I've not re-tapped a hole before-what is the procedure-besides what I
will get in the typical repair/instruction manual?

Thanks!

Michael