Depends...
If they fight in the afterlife and/or Goku is dead, assuming the powered SSJ2 gives Gohan the exact same boost as Trunks', Goku still has the advantage thanks to both a power advantage, greater fighting experience and access to a wider range of techniques, including Instant Transmission (a technique Gohan had trouble to deal with).
If Goku is alive and fighting in the living world, though, he might not last long enough to defeat Gohan.