Oh dear...I just realized your LeSabre is the same year as mine. I can't say that I'm completely certain that it won't fit, but I'm most of the way there. Note the differences in the stock grille size and shape between the 92-96'* and the 97-99'*:
The older ones have the same grill area but then they also had a body colored piece around the outside, whereas the new ones meet directly with the hood. The end result is a smaller grille piece for the newer ones.
However the portholes are a perfect fit for just about any H body and newer LeSabre. They're a bit pricey, but they're good quality and are nice looking. The owner of the green car above found his by going to Ebay and searching for "buick portholes".
These are the ones he bought (I think):
There are also these, but I don't know how good they are: