Holley 2-bbl on 273

If it's a Carter BBD, it's probably 265 CFM rating, the 318 BBD was 285 CFM. A 383 and 400 two barrel had a 365 CFM BBD with a bolt pattern between the small BBD and a Holley or Autolite two barrel. A better choice if your hellbent against swapping manifolds or don't have a manifold available for the odd angle 273 bolt pattern is a four barrel adapter and a 390 CFM four barrel. Your cruise economy and response will be better cruising around on the 195 CFM primaries.