Re: 4 point harness
I didn't even think about the stock seats, you are right. If the holes were cut through the seat without disrupting any support members, it may work. But I am not sure exaxtly what frame system the seat itself uses. I would worry about maintaining the integrity of that head rest after cutting holes through it. But then again, it may work without ever interfering with any of the seat framing members. I might be inclined to just buy new seats if I were going to put a harness in. But It's not my money so its easy to say that.
'88 Wrangler 258 i6,Weber, Rubicon Extreme duty 2.5"