Intakes and stuff

The 345 and 392  are the only two motors that 
have 4bbl manifolds available for the factory
V8's.   They are interchangeable from a 345 and
the 392, but will not fit the 266 and 304

Spread Bore :
Found on Scouts and Travelers
The spread bore manifolds had Carter Thermoquads
installed from the factory. This manifold is best suited
for bottom end power.  With small primaries for economy
and very large secondaries for power it makes a good
double duity manifold.
Carbs:
Carter Thermoquad
Carter AFB
Rodchester Quadrajet
Edlebrock Peformer  w/ adapter
Holley marine
Holley Pro-Jection
Preditor

Square Bore: 
The Square bore manifolds were installed on Travellals and 
heavy trucks. These monsters can be found in many junkyards
and the early manifolds are usually high rise with no EGR.
The most popular carb by far is the Holley 4bbl
Carbs:
Holley 4bbls
Edlebrock Preformer 


                          Spacers and Adapters
There are two spacers that are very popular.Mr Gasket and
Edlebrock. The first is a open hole adapter for the spread to square
application. The second is for the same but is of a four hole design.
The Edlebrock four hole spacer is more suited for bottom end
gains.  I do not recommend using a adapter for the 266 or 304s
for using a 4bbl. They just don't flow correctly.



As with the heads the ports in the manifolds are very restricted
and should be opend up for maximum performence.  Look at the 
exhaust ports, they need it the most.