Originally Posted by Jebbysan

The 600cfm 80457 carb on a stock 350 is fine........
If the carb is leaking out of the sides of the baseplate like yours seems to......it is bleeding bad from the boosters.....there are three things that can cause this.
1) Bad metering block gasket on primary side, secondary side, or both.
2) Blown power valve. The Power Valve adds the equivalent of 8 jet sizes to the mixture during different situations and if blown will just add that much all the time. I
3) Clogged high speed air bleeds. If the booster can't draw air through the air bleed along with fuel....it will just draw straight fuel.....
All three of the above conditions create a "dribbling" from the booster down the throttle bore......when the engine can't use it, it just floods above the throttle plate and out the gap in the throttle shaft/throttle plate.....to the outside of the carb.
The 80457 does not have a secondary metering block and only a metering plate. These almost always bleed through if they sit without fuel for months at a time.
All your carb needs is a good refresh......AED makes a kit pt# 4160 that has everything you need. I would advise you to rethink the fuel inlet on this too......there are several ways to route the 4160 style drivers inlet to the pass side fuel pump......here is what I like to do:

Above pic has a 180 degree fitting as the air cleaner is not dropped base (1956 Bel Air)....dropped base air cleaner will use a 150 degree fitting......the -6 AN adapters at the carb end and fuel pump end are available from the major fitting suppliers.
The L-79 327 from 1965 to 1967 had this style carb on it from the factory and the reproduction fuel lines from a Corvette vendor can be adapted as well.

That is a circa 1990 Edelbrock Performer intake that accepts either square bore or spread bore carbs.

I disagree with this carb being a downgrade in performance as a stock 350 at WOT past 5500rpm will never utilize a full 600 cfm of flow. The Q-Jet 750cfm is an upgrade IMHO becasue of its tiny primary venturi to create super high velocity from its stepped primary boosters.....this for a make a snappy and efficient engine due to excellent booster signal and emulsion.....

I could pull this carb from that engine...bench it in three hours and have it back on the engine running proper........you can too!

Jebby