After rebuilding my original 2bbl carb for my '70 Malibu, I noticed after removing all the soot that the front portion (the front of the steel mounting base) has had some rust build-up over the years. I found out that this was common for the two-barrels. What could I treat it with to prevent further rusting when it goes back on the engine? Would Por-15 work? It isn't exactly a high-temperature area like exhaust manifolds, but it does get hot in that area. What would work?

The POR-15 will work fine. My entire engine is painted with it. My intake is done in silver though I don't recommend it as it still looks shiney and clean but over time it has turned a greenish color.

Kevin-

So did you use high-temp. Por-15? Also I should have made clear this is going on the INSIDE of the carb base, not on the outside.
Please help.

No high temp I just used the regular stuff - no problems. This stuff really sticks to clean, porous metal. As long as this is not a machined surface I'd try it. The worst thing that can happen is that it'll start to flake off so keep an eye on and if it starts then remove the rest. It is not affected by gasoline.