As a service to my fellow bookbinders, I am offering some of the papers I use for my books for you to use in yours! I buy it here: https://www.thepapermillstore.com/superfine-white-paper-35-x-23-in-24-lb-writing-eggshell-1500-per-carton.html and get it custom cut.
This is Mohawk Superfine 24# text-weight paper, in white with an eggshell finish. It is awesome. It is also grain-short! This is a perfect size for pocket notebooks.
If you only want one ream, drop me a line and I can give you a cheaper shipping rate.