Gunpilot, I put a Marbles tang sight on my Puma 454. It extends the sight radius from about 16 inches to almost 26 inches. It is adjustable for elevation and windage. Cost is $125 retail plus the cost to have a hole drilled and tapped. The Marbles sight comes with the front and rear screw.
The weather has been pretty miserable, so I have only shot it a few times with the Marbles sight. It sure looks nice. I'm anxious to try it this next weekend where I can shoot it from a good bench rest.
Regarding shooting high, what weight of bullet are you using? Heavy bullets shoot high at fairly close range. A lighter weight bullet might be better. Turbo