Agreed, the 318 was a "bread and butter" engine by that time and no performance 2bbl intakes for it.
If you need a higher-cfm 2bbl, the next-up option would be the 1.56" throttle bore Carter BBD 2bbl for the 383 2bbls. Chrysler never did use a 500cfm-area carb, BUT GM did, starting in 1957 on some Pontiacs. Later to on-and-off use them on in the later 1960s-middle 1970s on Chevy V-8s and some Buick 350s, too. At least for USA-spec engines. To use the Rochester 2bbls, you'll probably need the same adapter used for aftermarket 4bbls to mate the GM linkage to the Chrysler linkage set-up.
To me, these big Rochesters drive just as good as a spreadbore QJet carb, up to about 3/4 throttle on a Chevy 350. Might not quite be 500cfm, but probably about 450cfm. Putting a 500cfm Holley 2bbl on an intake manifold with existing 1.44" throttle bores will mean the 500cfm carb will NOT flow to its rated potential, but less, with the adapter. Yet the adapter will be needed to interface the Ford mounting pattern to the normal mounting pattern, anyway. Probably better all around to machine the mounting flange to the 1.75" throttle bore diameters and use a factory base gasket than not.
With a drill press and hole cutting lathe, you could enlarge the existing holes in the throttle flange pad to 1.75" each. Then drill and thread new mounting holes for the bigger bolt patter. You can find an illustration of those gasket sizes in the Holley Sniper 2bbl service literature, as I recall. Yep, Holley Sniper EFI 2bbl models.
There were a few years, about 1968 or so, where the OEM 318 2bbl manifolds looked very much like a performance single-plane intake manifold. Still carried the same power and torque rating on the motors, though, but they did look neat. If you need more torque, a massaged dual-plane might be best.
Just some thoughts,
CBODY67
