Correct, the 17054911 is a Service Replacment for the 455 SD engines.
The SD carburetors were set up with quite a few different calibrations. They always act a tad lean and need recalibrated to work correctly. What jets and metering rods are in the carburetor?
If you are having secondary transition "issues", first order of business is to replace the secondary plastic cam and spring. I would also test the choke pull-off opening rate, some were pretty slow and can cause a delay or stumble when going quickly to full throttle.
Also check the POE system and make sure the well fill holes aren't plugged up.
Might want to try bending the secondary hanger up slightly, or finding a taller one.....Cliff