To resolve your problem, you will have to start at the basics. First, run a range rod (howell) down the barrel and insure the chambers line up correctly with the bore. The rod should NOT hang up on the chamber mouth on the way into the cylinder. Then slug your bore and verify that your cylinder throats are correct for your bore. If the bore is .451, throat should be .4515 to 452. If the bore is 452, throat should be 4525 to 453. Buy bullets the correct size.
You can correct for elevation to a certain extent by experimenting with bullet weight and speed. Lotta Load testing. Or, just find a load you really like that is accurate out of your guns. Then, take a leather pad, some blue painters or masking tape, with a nice new sharp fie to the range and start working your front sight down if your gun is shooting low. Shooting high, front sight needs to be built up.
You can't correct for windage with the load. You correct for windage by having the barrel turned ever so slightly by a gunsmith. It isn't real expensive and only takes a few minutes. HOWEVER. Insure your gunsmith has a barrel vice and a dedicated frame wrench. Ask that question first. If he/she doesn't have a frame wrench and barrel vice, find a different gunsmith.
You said your gun is shooting 6 inches left. As you look down the sights from the REAR, the barrel needs to be turned to the LEFT. You'll want to turn the barrel about a 32nd of an inch then shoot it. Go slowly. Not more than a 32nd at a time.
Coffinmaker