Since your hangers (at least on the passenger side anyway) aren't factory, it's likely you may be able to adjust them accordingly by putting a bit of a bend in the hanger rod or adjusting something, assuming the same on driver side. Most tailpipes were manufactured with a bend that has tolerances, and that meant you could have ends that may or may not be placed where you want them to be. I've seen factory pipes staggered from side to side like yours. GM Quality + 1980s = Water + oil.
I can say, if you had factory mounts, there would be only a very small amount of adjusting you could do with the mounting brackets anyway. The brackets and such were placed where there just wasn't going to be much movement available. You'd have to do a bit of bending on the fly.
If you don't want gasses building up under the car while sitting and idling, I'd probably place the driver side out just a tad more to match the passenger side. That's just me.