Hey, sweet!
You guys just hit on one of my forgeten pet projects!
Somewhere here I have a win94 take off barrel in 30-30 that I bought cheap 7 or 8 years ago for almost this exact wild cat; I had come up with the idea of necking 357s to .30.Then found out it wasn't a new idea, found some sizing and load data, and bought that barrel. Then it got "back burnered" and I never got an action for it..
I should really pick up a used single shot and order that 30 Badger reamer!
hmm... a buddy has a H&R handi in .410 that he almost never shoots... hmmm...