Unless it is aimed at Firebird, the glovebox liner is probably still to suit a Camaro like the original kit. May have changed.
Different reason, but the RHD converted setup in my car saw the glovebox lining also shortened. Naturally, it had been done quickly and cheaply and most would be happy about it. All they did was lop off the end wall section, and fold a new rear wall out of aluminium, fold the sides around and riveted. It's neat, but can always be done better. Turns out it also had clearance to the AC setup and heater box so I picked up a couple of original spares, will alter a new one when the time comes.
I could grab a photo of the altered liner if you like, just for ideas if you have to go down that path.