I don't know, possibly not, as the 1.8L is probably a "sleeved down" vesion of the 2.0L, (depends on the bore/ stroke) you would have to examine the 1.8L head carefully, take measurements, and compare it to the 2.0L head

If it was me i would probably use the 2.0L head, i would get some expert advice on how much to skim off it, and the type/ thickness of head gasket to use, i would clean/ smooth out and polish the combustion chamber and all ports, and match them to the inlet/ exhaust manifolds

really depends what you want to do/ how much you want to spend

i might use (1 grade) colder plugs and run the engine a little richer (bigger jets etc)