You've got the heat shields on right but the carbs are upside down.
Since you're looking at the top and the float bowls are on the bottom
you can't see them in this pic. They ARE HIF6 carbs so the bowl is integral
with the body, unlike the earlier HS6. Consequently you don't need different
bowls for different angles, either.
The bowls are closed by a bottom plate held on by 4 10-24 machine screws.
If they leak, it is not because the screws are not tight enough (usually)
and if you tighten them too much you will bend the plate.

The balance tube is the aluminum part that holds the two halves of
the manifold together. It has a fitting and a hose coming out of
the center for a breather/pcv/brake booster connection.
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George Downs, Bartlesville, Oklahoma, Central US