Just to echo that there is no stock 1.6 ratio option. You'll have to look at the adjuster bolts. RAU re-drills the adjust at an angle to change the ratio. This would lead me to believe that there is a different type of adjuster bolt in there. There is one other possibility (that I'm aware of) for high ratio rockers, and that would be the Thomas rockers. They're magnesium and haven't been made in ages. I wouldn't think you want those as I would expect a bit of metal fatigue, if you could even find them anymore.
If you're in the market for higher ratio rockers, the ones that Matt has at VintageInlines are high quality. I have a set of RAU rockers and I love them. I prefer the shaft mounted ones over the YellaTerra ones. The YT do appear to be high quality, but I didn't want to have to switch over everything (different type of lifters, oil through pushrods, and head oiling modifications are all required). The shaft-mounted RAU units are drop in. The set I got even came with both types of the front pedestal. I don't know if this is standard practice for them, but showed that they pay attention to detail.
