Well i did a little math.
Based on the idea that it's hitting 12 inches high at 100 yards and we want it to be hitting closer to 0 at 100 yards, that would mean that the front sight would have to be .028 inches higher.
Doing a little rough measuring it seems the current sight is about .425 inches from the bottom of the dovetail to the top of the sight. maybe a hair under that on mine.
That would suggest that a sight of .453 or higher would give you a zero at 100 yards if the elevation ramp were removed.
That would seem to suggest to me that a .50 sight should resolve most of this problem on the ranchhands.
of course i don't know the exact velocity of the bullets, but using some educated guessing if you are 0 at 100 that should put you about an inch high at 25 yards, a hair over 2 inches at 50, and dead bang on at 100 (assuming something like 1350 for a muzzle velocity). And that's at .453. Going to a .50 front blade should allow you to drop it even more so you were hitting low at 100.
I'm not sure what the size of the front sight dovetail is, but I'll call rossi and find out and then i think it's just a matter of finding the right front sight at about .50.