maya 2 unreal

Hey Gang
Question. after setting skeleton bone orientation in maya Im seeing quite a change in the FBX import to Unreal. When applying animations to characters, also viewing odd mesh deforming as a possible result. Chest caving in, Painted Maya weights not binding the same as in maya. Mesh and animations looks fine in Maya but when exporting to Unreal there is definitely a big difference.
In Maya we are modeling in Y up axis to accommodate Human Ik and Mocap. Fr animation we are using Unreal Mannequin library plus custom animations from Mocap and Hand.
Thanks for

any help