Got this done today. Doesn't look any different, but feels smoother.
I'm not sure it actually started with a 12" radius, but it's got one now, so hopefully that works out well.
Tomorrow arvo I'll probably get a chance to start the CA finish. That's making me a bit nervous, but so far on this and the tele my experience is that you'd pretty much have to be trying to make an unrecoverable mistake, so I'm sure I'll manage.
I'm planning to mask the neck completely, and make a tape "dam" to stop the glue running off the top of the fingerboard. Plan is to keep the CA finish just on the face of the fingerboard, and then finish the fingerboard sides in a neck clear coat or even just wax or oil. I sort of want to CA the sides too, but I can't think of a good way to actually do it.