I would expect handedness to show up with models appearing inside out, as the tri indices would all be wound backwards. It seems more likely that the handedness is the same, but the choice of world vectors in the modelling program is different than the one you are using. For instance, I generally think of y+ as up, and z+ as forward, yet blender which i use for modelling use z+ as world up. So at export time I must apply a 90 rotation to align my model so that it is good to go for my projects. If it truely is a handedness issue, then the solution is to invert 1(or all 3) of the coordinates(so point p(x,y,z) = p(x,y,-z) or similar), and swap 1 pair of indices per triangle(so that a triangle t(i0,i1,i2) = t(i0,i2,i1).