You'll need an adapter to mate the Holley to the Chevy manifold. The most common 3-bolt Holley carb was used on a 239 cubic inch flathead V-8, so the calibration should be pretty close. It will have a 15/16" venturi diameter. Watch out for the slightly larger carb that was used on the 55 Ford 272 engine- - - -it has 1 1/16" venturis, and it will definitely create a flat spot on acceleration.
Jerry


"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!