Installing an un-drilled FSB on an already drilled barrel - any pointers?

So I cut off my FSB a while back when I added a FF Rail that covered it, but now I am cutting the barrel down to 12.5" and want to go back to a 7" rail and FSB for irons.

I'm going to buy an un drilled FSB and planned to install it as follows but thought I would ask for any tips.

I plan to punch the pins out then clamp the barrel in the mill vice after running a drill bit through the holes before removing the old FSB. Once I have the barrel clocked to the chuck, I will hammer off the FSB, hammer on the new using a level on an extended front sight rod I plan to turn on the lathe for the setup. I'm hoping that by leveling the 3" "front sight post" I'll be all plumbed up to drill the new FSB and will only have to measure off the distance between holes for one movement on the table.

Clear as mud? Any better ideas?

Appreciate any tricks you might share.