If your SAI and Included Angle are significantly different
from side to side, then I would suggest a closer look for bent parts. If they are fairly well matched, and simply different from the "specs" carried by your machine, I would not sweat it. As you probably know, these angles are not adjustable.
As for caster, the negative specs are a throwback to "easier steering effort" days and are widely disregarded now. Caster matched side-to-side is much more important than the absolute number itself. If you have sufficient range of adjustment, go for
more positive. Also consider offset UCA bushings (installed according to instructions found in
this thread) to get it even more positive.