.22 LR is .223" diameter. .218 Bee normally uses .224" bullets. The original .22 Hornets had .223" bores, whereas the newer ones all have .224" bores. I'm not aware of any T/C .22 Hornet barrels that have .223" bores.
All that said, you could do a .218 Bee barrel off of a .22 LR barrel, but you would have to limit yourself to the .223" bullets that are out there for the older .223" Hornet barrels.
And that said, why not just buy a .218 Bee barrel to begin with?