Since you are going to run the expander plug into the case to create a new case mouth flare, anyway, that will take care of any remaining crimp in the brass.
Since there was no firing to expand the case, the "neck" will be the same as it was and the same as it will be after you use the expander on it, again. Bullet seating should be the same, crimp the same, etc.
IMR 4227 is a fine powder for some things, does pretty well in large .44 and .45 cal cases, its too slow for shorter or smaller cases. Manages tolerably in the .357 there are a couple loads for it in .38 SPL but its not at its best there.
Not suitable for .45acp or 9mm or anything in that case capacity range, its just a tad too slow for efficiency.
Often (not ALWAYS but often) a slower powder burning "dirty" means incomplete/inefficient combustion. SOMETIMES, the cure is simply working up to a heavier load with that powder. Sometimes, its not, and going to a different powder will be necessary for both power and (relatively) clean burning.