Hi Martin,
I hope this finds you in time...
I too have recently been through the process of selecting a stick on vinyl front number plate and think the biggest thing that determines the quality is whether the lettering in subsurface rather than applied to the surface of the number plate.
As Ralphmusic has suggested
www.onestopnumberplates.co.uk produce full sized, subsurface and reflective numberplates and I ordered one and can attest to the quality.
However, as we all know the standard British numberplate covers quite a large area on the front bumper and due to the shaping of the front bumper of the 718 GT4 and will not sit entirely within the small flat portion of the 718 GT4’s front bumper (either sweeping forwards on the lip to the radiator intakes, sweeping up over the nose of the bumper towards the bonnet or a bit of both).
Instead I went for a ¾ sized stick on number plate from
https://www.fancyplates.com/buy-plates/uk-show-plates/ which is also subsurface, reflective and equal quality to the onestopnumberplates but crucially fits flat on the front bumper.
Following is a link to a photo of my car with ¾ sized numberplate
https://photos.app.goo.gl/ffPUTPu9X57bTBxy5 (I can't seem to work the attaching photo thing in the forum...)