[snapper]

Hold your horses
The chamber size on the heads is different
You will have to much compression with a 1600 head and not enough with a 2.0L on an 1800

There are a number of differences with the 1.6 and 1.8 Eco Pinto's
The standard 1.6 Pinto has a combustion chamber of 38cc whilst the 2.0L has 48cc
Your compression would be 11.5 to 1 or more, with a standard cam you would need avgas to stop det
Your standard Pinto pistons are safe to 10.5 to 1 perhaps a little more but not much

A bit of history

The 1600 head was used for increased compression on a 2.0L but after porting the inlets and unshrouding larger valves when fitted, this increased combustion chamber to somewhere around 40cc, unshrouding and using a standard old Ford gasket @ 1.62mm kept compression manageable.
Lairy cams also reduces compression pressure, later closing of the inlet valve
The 2.0L injection head is now the one to modify

Putting a 2.0L cam in a 1600 is still a cheap upgrade and may add 5bhp but why upgrade a 1600 when you can bolt in a 2.0L for much less