I went with more modern blocks and precut paper and I’m so glad I did.
https://www.amazon.com/3M-SandBlaster-Pre-Loaded-Sanding-3-7-Inch/dp/B000FCIMYO/
Get three. That way you can load them with three different grits, saves time when working.
Inexpensive precut paper in many different grits:
https://www.amazon.com/gp/product/B075WXT1Y2/
This kind of setup will make sanding so much more efficient than the traditional hard rubber block. I tend to use 120 or 240, then 320, then 600.