[Dave at Pelican Parts]

Not only the cost, but also because the 1.8 heads don't crack as much as 2.0 heads do. They have more material in them, and they seem to resist the tendency to crack better.

That is quite likely why the 2.0 heads were replaced--too many cracks and/or a dropped valve seat.

Of course, it could be a 1.8 built up into 2.0 displacement--check the engine serial number as mentioned by jmcleod.

--DD