afni.nimh.nih.gov

3dWarp allows the -gridset option to make the output match a specified dataset. One could also use 3dresample to force the same grid in a second step.

Whether deobliquing is necessary is more a question about the complete analysis. Deobliquing is not necessary if analysis is done on a standardized talairach type space, and anatomical and functional data are equally oblique and overlay well with each other.