Nah, as long as I know I'm supplying for the right I'll soak up the extra 50p or so the cable costs
but there's no point stuffing extra cable that just needs tidying away somewhere for the right hookers.
You'd *think* that the dash would be a mirror image... but this is Fiat
so I still have a dozen stainless plates that fit nothing lying around somewhere. The LHS vent is the same height and width at the top, but about 8mm narrower at the bottom (it's nearly but not quite rectangular) so you'll need to measure and cut to taste. But it's only a hacksaw cut (and the CF should be easier than SS) and a file to round the bottom left corner again.
I'm loathe to do it here without a LHD car to practice on, so I'm afraid you have the pleasure.
edit: recommendation - remove the CF plate, make a paper or card template, adjust template to fit the hole, transfer dimensions back to CF plate and *then* cut.