Ouch. That's a long ways to go to the range.
That's a nicely redone 1891 that you have. Measure the distance between the sights and then you can use this formula to determine the amount to move the sight if you want to move the zero to the right. Remember that with the front sight, you move the sight opposite the desired movement on the target.
Sight radius in inches / range in inches X error on Tgt in inches = sight correction
US Army Distinguished Rifleman
Washington State Distinguished Rifleman
NRA Police Distinguished Expert