Dual quad manifold
I run two 500 Carters on my 340 with an old Eddy D-64 intake for use with the 273. The ports are small 273/318 size but bolts on fine and works just great.
Personally I never go back to a single holley unless I was bucks down. Engine idles great and gets good mpg while driven light and still packs a punch WOT.
Has smoother-more even throttle response, linkage is 1 to 1 and both air doors removed on the secondaries