The heads do interchange, including the cams.
The stock 1.6 cam is a good upgrade for the 1.3, with about 10 degrees more duration, and .5mm more lift.
The 1.6 head has bigger valves. .5mm int/2.5mm exh.
Its a good idea if you are looking for more power.
If you can, resurface it for more compression, .5-1mm.