Yep, the relatively slow, 1:12~1:14 is "traditional"... sort of. Kinda old style compared to more modern 1:7, 8, 9 twists... but then again, there weren't too many heavy bullets in .223 not all that many years ago.
Doubtful you will have much success using a longer/heavier bullet than 55/60 gr, as it may not stabilize, but you can easily go down to 40 gr.
Cheers,
C