That is a Rochester Model B, they began using that carb in the '50s I believe, through around '67 or '68. It was stock on the six cylinders, the one for the 292 was slightly larger though(but same family).
You can't rebuild the one you have? I bought a carb at AutoZone and it was nothing but trouble. It was a later Rochester on my 292, but anytime I slowed down the RPMs would slow way down, sometimes stalling. Even going downhill at a steep grade would do it. No matter how I adjusted the float or anything else, nothing helped a bit. I threw that POS away and found an old Model B, rebuilt it and drilled out the jet and its ran great ever since.
For a replacement I'd use a progressive 2 bbl like Eagar1 said. Tom Langdon's Stovebolt sells them, along with the adapter for the stock manifold, and throttle linkage, and I'm sure he can tell you exactly how to set it up.
http://www.stoveboltengineco.com/acartpro/
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Andrew
'69 C-20(292, 4-speed) Retired Daily Driver
'64 C-10(250, 3-speed) Fixerupper
'97 F*rd Mustang GT(4.6L, 5-speed) Daily Driver
If I only wanted two pedals I'd have bought a bicycle. 