try to locate a PS-4 film copy attachment for your PB-4.
Simple and easy to use. The bellows
between lens and film is all important to maintain contrast in the reproduction.
Took a while to set up a good light balance behind the PS-4, but once that's done, copying each film is quick and easy to do.
I've used both the D300 and D800E on some test Kodak films I exposed just for the sake of testing it all, and there was no real advantage in resolution other than I could resize just a touch more if needed for the films I actually wanted to reproduce.
** the films I wanted to copy were old 50's Kodak slides when they first emigrated here. Turned out that all those films(mounted) were left in a musty corner of the house and they all developed mould!
While it's nice to have rather large tiff files from a slide scanner, the real advantage in using a camera is the ability to capture the copy in raw format.
The ability to whitebalance "to taste" is worth the effort.