We've been building Jr206s out of the adult ones by changing the coil and adding the clutch. Kind of an expensive way to go about it, but it's the only way we can fill customer orders right now.
That said, we've been doing the same thing for WKA animals....Take the 206 and cut the seals and replace the coil....then go about the rest of the build, machining & blueprinting, as normal.