It does not make any difference whether the model is FiveM ready or not. There's only two fpiu models out there (I think), so it shouldn't be too hard to find one that this livery fits on.
This livery is made for both engine6a and engine6b in Medic4523's Pierce Arrow XT pack, which can be found in the link below.
https://modification-universe.com/forums/resources/pierce-arrow-xt-pack-vg.61/