Rule of thumb is you need to be able to sight the rifle in with the rear sights (no matter if the sight is pinned to one side) in order to slip or re-index the barrel in the rifle (upper barrel socket) and the rifle still functioning.

With the rifle shooting so far off, the only option is to pull the barrel and confirm that the barrel extension pin is indexed with the FSB (read pin just bent).  If you find that the extension pin is not even close to the same plain as the FSB, then there is not way that you will be able to re-index the barrel in the upper barrel socket and still allow the bolt and extension lugs to mate correctly during lock up/unlock. On something like this, you need to pull the FSB and pray that the barrel gas port is correctly indexed with the barrel extension pin, and only the FSB was installed canted to the port/extension pin plain. If in fact that the port and pin are aligned, then there is the option of installing a FSB via the setscrew method, or filling/welding the old taper pin slots and correctly installing/drilling the new slot for a correctly indexed FSB.

If you find that the gas port and the barrel extension pin are not even close to being on the same plain when you pull the FSB, then you have a tomato stake on your hands since it's cheaper to just buy a new barrel then to have the barrel corrected.