4 Barrel on 273?

E-brock Performer has small ports that match up well on a 318, should work on a '66 273. I ran one for years with an 1850 Holley (manual choke, side hung floats, and the cheapest four barrel Holley offered, I think I payed 69 bucks for mine on sale) on the 318 in my 67 Coronet. Used to average about 19 MPG overall.
The Performer also has a spreadbore carburetor pad allowing the use of a Thermoquad with it's tiny primaries. Setup and tuned right, a Thermoquad might work really well for low speed, part throttle operation on something as small as a 273, and the adaptablity of it's air valve secondaries to a wide range of engine sizes is well known. After the demise of 340s and 360s in passenger cars, four barrel versions of 318s were offered from the factory with them before Mopar started using the GM Quadrajet.