I've been shooting a '92 Rossi .357 for many years. I wouldn't worry about the twist; shoot first, then if there's problems, start digging. Remember the length of the bullet, not the weight, is what determines the twist needed. I've successfully loaded the 170 .gr. Sierra in my Rossi as well as a 180 gr. cast FP I cast myself, running ~1700 fps. The deer and hog I've killed have been with the 180 gr. cast bullet in HP form which, depending on the size of the cavity weight 162-168 gr. This one came from the hog-
8/.357 180 GR. LBT- WFN Similar bullet in solid form.
Regarding your choice of powder (W-231), published max is 6.9 gr. which is probably going to around 1200 from a revolver, and you can add roughly another 200 fps for the carbine. So 1400 fps isn't too shabby at all and you're using less than half the amount of powder you would be using with H-110 et al.
I personally am a fan of heavier bullets in this caliber and wouldn't under any circumstance go under 158 gr.
35W