The first thread in the Workshop Forum ( sticky, Welcome to the Workshop: How do I / Where do I / What do I / answers are here ) has a ton of links to HOW TO and WHERE TO find parts. Or Texas Knife, most any knife supply will have pin stock in most any size.

But, yea just sleeve the hole. Just make sure your hole is straight or that you epoxy it straight if there is slop. Drilling a tapered tang, can be tricky.

You can make a jig with a piece of wood and piece of pin coated with paste wax to hold the sleeve in place as it cures, if the hole is larger than the pin.

Cut your tube with a piece of rod in it makes it easier.