There is also the .224BRM, more of an "improved" 30-30 case. Blown out body taper, with a 30degree(?) maybe 35^ shoulder. Which is a brainchild of Eben Brown (eabco). But Eben is alittle touchy on rechamber jobs. If the exsisting chamber isn't perfectly straight to the bore, he won't waste your money or his time. But,,,
Another option, would be Mike Sirois, of On Target Technologies (MBMCO).
He use EDM machining, rather than reamers. And if there is enough to "clean up" can rechamber using desired case dimensions.
As for the rest, I don't have any personal experience with what you are thinking. But do agree, that performance would be close to the 22-250, with about any wildcat designed on the 30-30 full length case.