I just did something similar with a CB450 - put on comstars from a 79 CB400T2.
The rear wheel was offset, like you're experiencing.
It was easy just to cut and grind some new spacers for the wheel. I used a level and a plumb bob, that's all you really need.
I lucked out, and when I centered it, the sprockets lined up nicely for me (that was a major concern of mine).
Worked out great, because I wanted to retain the 450 swingarm.
bill
