Welcome, glad you found us!
In all honesty, there isn't much to go wrong on that car. The L27 will run forever and ever, usually in spite of itself. The 4T60E transmission is hit or miss, but generally okay as long as it isn't relentlessly abused. So, reliability-wise, you don't have much to worry about.
Lowering is an issue because of the rear monoleaf. At one point, Intrax and a Canadian firm called Birchmount made rear lowering leafs. They've both been out of production for quite a while now. Your only hope would be to find someone selling a used/NOS one. As far as ride quality goes, I've never ridden in a lowered first gen that was anything remotely considered "comfortable". YMMV.