I had a SD on a 72 440. Worked well.

Put a RPM on it and it was much better. Little bigger carb than the Holley EFI I was running, 750 vs. 700. Had much better low end with the RPM.

Running a SD on a low deck currently. I like it but can't help but wonder if that is why I seem to be down from previous MPG's from other 383s I have had with the stock intake on them.