Justice Trimble: since you need to move your rear sight in the direction you want your bullet to go it seems that you may have hit upon the problem. A 'right leaning' rear sight should cause your poi to be to the right. As for hitting high, tang sights sit higher than the barrel mounted rear sight and you will need a higher front sight to bring the poi down to poa at your preferred distance.
You can obtain new Winchester front sights from Browning/Winchester or from Brownells. The Brownells catalog contians a front sight chart to help you determine the overall height of the front sight you will need. Any local dealer that stocks Winchester rifles should be able to get the address for Browning/Winchester and you can then get the telephone number. I have found the Winchester parts people to be very nice. HTH. Mikey.