I am planning to use Fuji SK2 components with the Fuji winding checks. I assume that I want to purchase the winding check that is closest, but smaller, than the diameter of the blank at the point of installation. I assume, further, that I would ream the winding check to fit. Am I on the right track?

It is probably better to get the next larger check. These are pretty small and you would only be able to ream them if they were already glued onto the reel seat. If there is a slight gap between the blank and check just put a small wrap in front of it and seal it up with some thread finish.

Those Fuji checks snap in so no need for snug fit to keep centered.

I found these SK2 winding check ver y good, they fit IPS16 too and VSS16 with a little work.

I've been using them with the ECSM seats also as an alternative to epoxy ramps.

They fit well and are available in .5mm increments. We expect to receive a shipment of new metalized winding check soon for the SK2. They will be silver, gold or black. They look really good and fit perfectly, like the current ones.
It's usually best to go bigger rather than smaller. You can easily hide the difference and you save the hassle of a potential melt down or burrs in the plastic if you ream too fast with a drill.