The rear mounts on the 05-07 Choppers were offset. You can see them on the BDM website.
Otherwise you could go with Kuryakyn and there BD peg mount for their pegs.
I paid about $100 for a set of chrome adjustable offsets for a Bourget. They are indexed so you can rotate them to adjust the height. I'm sure custom chrome or any of the parts catalogs will have them, but you'd have to switch to harley style rear pegs.