afni.nimh.nih.gov

The sform_code of 2 is ambiguous. Is that data in
standard space? If so, then then T1 dataset should
be as well. Otherwise, the overlay should be in orig
space.

Sometimes FSL includes a comment about the space
in the NIFTI header, maybe in the 'descrip' field. So
maybe you can verify the space from the output of:

nifti_tool -disp_hdr -infiles fun.nii

(or possibly adding '-field descrip', if you wish)

- rick