We use moped hubs on motored bikes, and we build some real hotrods. They work very well. They are same basic drum hub like Worksman uses up front, but they're wide (130mm) and they have bolt on sprockets. You can lace one of thees hubs into a stock Simplex rim, not sure what the offsets look like though. Pat has pictures of them on his website, so check out his website:
http://sportsmanflyer.com/It's hard to keep up with all the latest stuff on the website, but if you go to the Sportsmanflyer flikr page, you'll see all the latest hardware, including a complete folder with lots of pictures of the hubs we run.
This link will show you just the hubs:
http://www.flickr.com/photos/sportsmanflyer/6023605271/in/set-72157627379714327/And this link will take you to the top of the flikr page (be sure to take your time to really look around, lots of cool goodies):
http://www.flickr.com/photos/sportsmanflyerWe always have lots of builds going, including some seriously fast bikes that we're working on now. As soon as we get thru those, we'll be building out a vintage Simplex with modern fourstroke power, either a GX200 or GC200. The plan is to build one out then offer a bolt in kit for other Simplex users. Pat builds some pretty high end stuff and Simplex setup will be of similar quality. It's always possible to build on a budget, but it takes more leg work to find the deals.
Rich
oh, and like I said before, Pat lists the worksman wheels (brand new) on his web site, he can make custom rear sprockets too.