You should be able to install the new panel without cutting it.

I have a 97 LS coupe and my panel is notched. But from all the times I've been working around that area, that little notch just gives a little extra clearance for the end of the steel brace bolted into the floorpan just behind the round access panel for the fuel pump assembly.

It seems to have acres of room though, so I would try to install the new panel and only trim it if absolutely necessary.