If the issue is body roll, which it may well be seeing that it has been lifted AND that re-installing the sway bar (which, incidentally, is also known as an "anti roll bar" in some countries) helped to some extent, I don't see widening the track as likely to have a significant effect.
Another possible cause, depending on what tires you're running, is increased "flex" or "squirm" caused by the increase in sidewall height when you switched to the oversized tires - again - I don't see widening the track as having a significant impact, but, I am curious as to whether widening the track, which would increase the twisting forces "at the tire" wouldn't cause it to flex more - try bumping the tire pressures up and see what happens.
I suspect the solution to your issue is going to be stiffer springs - my GV is sitting on OME springs, shocks & struts, and also has oversized tires - there was no noticeable change in "tippy-ness" when the suspension was installed, but the effects of the increased sidewall height was immediately noticeable (the tires were installed several months after the OME suspension was fitted), and that is why I used the term "squirm" to describe it - the GV on 70 series tires no longer corners with the precision that it did on 60 series tires.
Despite the fact that the center of gravity has been raised, the body roll is actually reduced because of the stiffer springs, the ride is firmer because the shocks are matched to the springs, and the handling is just shy of a good sport suspension - good enough that I can actually "pressure" some fairly pricey sports cars along the road to our airport - two tons of SUV is not supposed to be able to hang with a turbocharged Subaru Impreza WRX, and when you do it, the Subie driver is not at all happy.-