Smaller valves in a 1.6 head and not ideal squish (piston top to head distance) if you are putting in bigger valves, open up the throats behind the valves, and relive the chamber walls you will see benefits.
Just bolting a 1.6 head on the low comp block, not sure you would see much difference.
Oh and the 1.6 cam is shorter duration than the standard 2.0L