Hmmm, that is not clear. Use the EPI for -dset2 and try setting -epi_base.
Maybe that will work, maybe not.
Or you could just stick with -anat and -epi and set the cost to lpa yourself.
You could even use uber_align.py and test a bunch of cost functions to
see what works. Try:
-cost lpa -Allineate_opts -source_automask+4
and see how that goes.
- rick