I wouldnt sweat that problem that much, just put it in, and take some spacers out just to keep it even, based in the bike you are fixing and please dont take me wrong, doubt the bike will explode or do anything wrong if the spacing in the rear wheel is off 2 or 3 mm in the rear axle.

With some bikes you have to be accurate with other ones pretty much whatever will do and this is one of those IMO.