Welcome to the site, Fisherman!
The 312 engine was available in Mercury cars in 1958, 1959 and 1960 and came from the factory with a two barrel carburetor.
I would not be surprised to find a 1956 or 1957 Ford or Mercury 312 engine with a two barrel carburetor and intake manifold on it, but it did not come out of the factory with them.

Goggle
www.ford-y-block.com for other helpful info. about FoMoCo y-block engines. IF you continue down the web page until you get to the section just before
Ordering Information, you'll see a toggle for
'Technical Information' and below that a toggle for
'Identifying 312 Engines'.
Regards,
NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York