Holley 2-bbl on 273

You'll need an adapter, this will do it. Mr. Gasket Carburetor Adapter Kits 1937MRG
You'll have some improvement in performance as well as over the counter access to jets and power valves if you need to tune it. But, if you have a small four barrel on hand, you would have improved driveability and mileage compared to either two barrel. The four to two barrel adapter on the Clifford \6 manifold can be turned upside down on your present two barrel intake if it has the slotted bolt pattern for the different two barrel sizes.