An engine with modern fuel management is cheaper to maintain and yields better fuel mileage as well as performance. There are a few choices that have to be made. Because of the differences in ECM's, which means that a different ECM may be needed. It is easier to "back date" the engine to an ECM, then the other way around. Meaning that it is easier to put a 1996 engine into a 1994 car that already has a 1.6 then to get a 1992 engine to work with a 1995 ECM. If you are swapping out a 1.6 to a 1.8 a new ecm may not reguired (use the sensors and such off of the 1.6). Read up on Miata engine swaps, which use a different ignition but still are the same type problem.
If I was swapping, I would go with a 1996 engine (1.8) and ECM. This is because of the advantages of the OPDII diagnostics.
As for pulling a small mountain with 5 people in your car, with a either the 1.6 or 1.8, don't expect to have a very high top speed when you get to the top. That is unless you add forced induction.
