I'd definitely do the water pump just because they're cheap and it's so much easier to do it right while you've got the engine out.
I've heard of the oil pumps being a known problem in some jeeps of that era - but can't say for sure if it's a problem in THAT engine.
Definitely follow up with that one on the jeep board. All I can say is I've got a 96 and haven't had a problem with mine yet.
Also ask around about the head on that engine. I seem to recall heads cracking from over heating - not sure of the year though, but know it was around that year.
Otherwise, from what I know of them, they're pretty bullet proof engines.
For parts - I have an advance auto close by - but got so tired of them I started using NAPA - better, but found they tended to be over priced in many cases. Always flipflopped between the two.
Recently started using CarQuest - and have been very impressed with them so far (though still limited experience). I'll continue using them exclusively until they give me a reason not to.
If you've got one near you it'd be worth checking them out.