Like most of the above, I have only 12V cars. Our '93L with 173k is going strong, and we have other engines up to 150k with no signs of weakening. (one engine has only about 8k since overhaul last April).
How is the oil pressure in your LS? That might be an indication. I've also heard of cams losing lobes, and you might consider measuring oil pressure, compression, and examining the cams if you're wondering about $ outlay in calendar 2008. I've heard of some auto trannies going sour about 150k miles (our '91L is one of them) but also of them being handled well and getting 200k+ from them.
Michael