Seeing that you are in the US I would recommend Rick Propas ( https://www.thepenguinpen.com ). He is an expert on vintage Pelikans and usually has a great selection of restored pens available with plenty of options when it comes to nibs and whatnot. Naturally there is a premium compared to pens bought from ebay or found in the wild but... you do get what you pay for.
Thanks for your help.
Yes. I checked out his site.
He has a few 400nn's. I'll ask for some writing samples.