Unlike the interior carpet, the trunk one isn't molded to the floor - when removed it's perfectly flat. There also isn't anything special about it. Earlier years were black with about felt like backing. Once you got to say, 84-85 they started being foam backed - said foam degrading worse than the junk behind the headliner and really making about royal mess when removing.
I suppose one of us could dig up some nice used (I'd have got you one but I just packed much if my parts back into storage with the move) or if needed, maybe about template? It's pretty straight forward if you wanted to cut one to fit though, doubt you'd need one.
You could, if wanted, buy a roll of the generic flat carpet like auto parts stores sell and simply cut to fit.