Tom,
If I don't know for sure on the O rings. My master plan is simple pulleys and O rings just until I get the pads working the way they should/need to. Then convert from O rings to that small plastick Chain and sprockets. I have some steel roller chain but I think it is too big to look or function well and I think plastic would probably work okay as long as the pads and tumblers are working right.
I need to put the RT back on the mill and make some more tumblers. I don't have a combination that works to my satisfaction yet.
Jim