How does the neck pocket look? A bit of paint in there can affect the angle and how it sits. By upward bow do you mean the 5th-7th frets are sitting higher than the 1st and 12th? Most of these kits have two way adjustment on the truss rod, so after its loose you can keep turning to adjust the other way. If you have a convex bend (high 5th) you can keep turning the rod anti-clockwise (looking from the head stock towards the body) and it will adjust towards being concave. If its too concave (5th-7th frets low compared to 1st and 12th) then tighten clock wise. Do you have a neck straightness gauge? Like a steel ruler or notched bit of aluminium?