Are you talking about sizing the bore or prepping for new rings?
If you're just prepping the surface for rings a ball hone will do the trick.
Sizing the bore is a different story. It's not the length of the stones it's surface area that does it right. You'll need a double stone/guide set-up for sizing to keep the stones from hanging in the ports. These things make doing big bore smokers a pleasant job. Small and medium bores are downright fun with this deal.
Here's a photo on a Sunnen AN-600 head.