I know I've seen somewhere on this site photos of swords with shims in the cross guard to make a tighter fit. Can someone send me a link, or post more photos?
I picked up a cross guard from the Albion Moat Sale, and the hole appears slightly larger than I will need. I think I need to shim unless someone has a better idea.

I recently closed an oversized tang hole by heating both sides with a propane torch and hammering both sides in turn (on an anvil). Use light blows--it closes easily but it's time consuming to file out a hole you get too tight. But I also use thin brass shims bent into an "L" shape and driven between blade and cross with a broad-bladed screwdriver as a drift.

Another Idea that has worked well for me in the past is to make the shims integral to the grip core that way they won't fall out with use and will center the cross as the grip is tapped tight against the cross eliminating the problem of trying to center by shimming both sides simultaneously. tr