Who is making that chambering reamer - today?
Is the barrel .458" groove dia.?
The originals were oversize, which complicates things.
Best to have a .458" groove. dia. Even then, the .45 Colt shoots .452's to .454's depending on the gun - they may or may not give accuracy in a .458" groove dia. barrel.
On the other hand, I used .452" Speer RN's in my .458 for grouse bullets and they shot well - into 3" at 100yards, but at grouse head ranges shot under an inch. The vel. was 1,445fps.
So - if smacked hard enough by the powder charge, the soft swaged factory bullets can shoot reasonably well.