With a properly adjusted carburetor idle/lowspeed circuit, altering the ignition curve is seldom if ever needed.
Off-idle hesitation is nearly always cured with larger downchannels.
Your Cadillac carb has around .046" downchannels and they need to be around .052"-.055" for your Chevy engine.
Also look for .035"-.036" idle tubes and .090"-.095" idle needle holes.
HTH