My pager thingy went off...
Had two actually. The first one my parents bought new. The second was mine.
1998 is a good year. First year for the 3800, last year rear disc brakes were standard. Make sure the LTZ has the 3800 in it. They could be had as the appearance package, which only got the cladding and still had a 3.1L under the hood and usually had just the single exhaust.
The motor will be the same as the bonneville as far as what to look for.
The body, like mentioned, look for rust where the front subframe mounts to the car, in the wheel wells, and around the gas door. Check the tops of the strut mounts inside the trunk behind the carpet.
For the interior, the leather seats are often ripped at the door side. Junkyard parts are an easy replacement, and Monte Carlo fronts of the same gen work, along with Grand prix and cutlass seats, but not sure on the year.
The Lumina is considered a Gen 1.5 because it maintained a lot of stuff from the Gen 1 w-body in design, but got the motor and stuff from the Gen 2 w-bodies (based off the Grand prix generations mostly) PCM support should be fine. Your center console lid should be broken. It was a feature GM had that sometime after 75k they were supposed to break if you looked at them wrong. If that doesn't bother you, and yours is good still, remove the console and sell it and you might make half or more of the purchase price back.
Sunroof on those liked to have issues. greasing the tracks, or replacing broken/worn parts can help. If it doesn't have one, even better.
As far as owning one, i loved mine. Would still have it if I didn't need cash. For $200, if it runs and isn't too rusty, you can't go wrong.
2007 Saturn Aura XR | 1970 Chevy Blazer 4x4 | 1970 GMC 3/4 Suburban 4x4