Welcome aboard!!
Finding a 1:9" twist barrel will be a little harder than you think, you'd have to physically check it before you buy it as there's no rhyme or reason to their production, a fluted barrel will have a good chance of being 1:9", but even it's been produced in 1:12". Can't help ya with that caliber, never heard of it, but lots here have rechambered Handis.
FWIW, the .223 1:9" twist barrels won't shoot the heavier, longer bullets that the faster twist does in other rifles, there's a lot of speculation as to why, from shallow rifling to oversize bores, but their reputation for shooting heavier that 60gr bullets is disappointing, but they shoot the 40gr-55gr bullets very well in the .223, whether the heavier bullets would shooter better if pushed a lot faster remains to be seen.
Tim