Turning down the shaft would be a possibility but we'd then have to machine a bushing for the standpost to make sure everything would fit. Some of the roller bearings are sealed but you must have a nice round shaft. I like the idea...they'd be replaceable and they wouldn't cause the shaft to wear oddly. Plus you'd shed a bit of friction in the process...I'd have to do some coefficient work but it would be there. As long as too much wasn't removed from the shaft (which could weaken it), it should be okay. But really the valve springs on a stock Stovebolt aren't that much.
