Arf, this might not be the solution to your problem but the possibility spurred into my head so me's figured to share, anyhow.
From my understanding, you're switching from the Legendary Items to Ringo and Delay's Item Pack, right?
Have you tried deleting everything in your Items folder, all except the folders therein? Then proceed downloading the item pack and replacing the item.cfg accordingly?
Me guesses the items are not showing up because there are some items/item meshes that are currently in your Items folder that are not being in use.
Me hopes this made sense!