Keep the 95 sensors and injectors--you need those for the 95 computer to work. They will mostly go in the same place. The big exception is the temperature gauge/light sender at the back of the head, since there is no hole for it in the later heads, so you will need to drill and tap a hole in the flat spot on the thermostat housing and extend the wire up to the front under the loom. You also need to check the fuel rails, since the plumbing on those changed a few times over the years, and if they are different keep the 95 rail.
The other consideration is the power steering pump and tensioner bracket which was changed in 1996. The later setup has a better tensioner setup but you will need a pump for the 98 to use it. If your friend has the pump you are golden. Otherwise you can keep the dorky 95 tensioner setup and pump.
For everything else keep your accessories (A/C, alternator, etc) as there is no reason to change any of that.