No need for the shipping expense, Wiley. I no longer have any big LN planes, just a 4 bronze, but I'm sure that I have an infill that will fit that size, even though it's not typical.
Actually, my favorite cast infill is this same size. It was something someone in the UK put together from a hardware store kit (I think) and is the best working panel plane I have, bettering my two norris panel planes.
If not, I'll pein something on the record plane that I have. This is a minor issue definitely not worth a double expense of shipping (Which is at least as much as I'd lose if I just outright bought a new LN and sold it at the end).
Thanks for the generous offer, though. It's never required and always appreciated.