Here is my method for alignment. I first make a dummy that fits the original camber very snugly and has the same diameter top as my reamers. Then I set the cylinder up on parallels and adjust the table till the dummy goes in the cylinder with out any bump as its square end enters the chamber with table locked and vise locked. I have a set of brass plates that go on the vise jaws before I stick in the parallels and use some old banding material to form U springs to hold brass plates and parallels in place. Once the cylinder is locked in lined up perfectly with the dummy, I run it through the steps until reamed to new chambering. So far it has worked very well.

Check here for my method
An unloved 629-1

Also, nice work on the cuts for the rear sight. I would square off the front of the new style sight you have.