If his hobby wasn't restoring old cars before, it might be now :~)
Looks like they've been kept pretty dry... just covered with dust.
Would probably have a lot of problems...mainly infestations and if any fluids were left in them, it would likely be very thick sludge.
Remember when I pulled the Beetle out of the field...remember that sludge that had slowly dripped from the gas tank? It was thick like rubber.
But that's nothing that can't be overcome!