Spring,

In your 470 you should first find out the pattern that it produces. From a rest, shoot 2 each of something like the following (500 grain Woodleigh solids), one shot from each barrel. Mark which bullet hole is from the left barrel and which is from the right barrel.

84 grains Reloader 15 - 2 shots
85 grains - 2 shots
86 grains - "
87 grains - "
88 grains - "
89 grains - "
90 grains - "

Then try it again with IMR4831

103 grains
104 grains
105 grains
106 grains
107 grains
108 grains
109 grains

The 2 shot groups should start out being HIGH and WIDE APART.

As you increase the powder charge, the 2 shots should move CLOSER TOGETHER and LOWER.

With this method you can often find a load that gives you an acceptable spread between the barrels and an acceptable POI.

Alternatively, and as a last resort, you can have a good gunsmith go to the range with you and file the sight.