Yet another '68 only part! Sounds like your passenger side one is original, they are a very different shape to the late ones, deeper and not as wide. I am needing a '68 passenger side visor (lhd) and in the meantime have late ones fitted even though they don't look right. You could always fit a later rear view mirror to fill the space in the cut-aways and not many folk would be any the wiser...
But I'm holding out for a second '68 visor. Wanna do a deal, your old one for a pair of perfect later visors? Maybe a couple of quid your way if your old one is nice.
Am sure splitty ones are completely different again and won't fit in a Bay.