I've always heard that the ROT of the 760s in 35 REM, 1-16"(?), was too slow to work well with bullets heavier than 200 grains, so rechambers to 358 WIN or 35 Whelen were generally unsatisfactory 'cause the heavier bullets that you'd probably want to shoot wouldn't work well.
IIRC, Paco Kelly recommended heavy 35 REM loads for strong rifles like the 760, but not applicable for the Remington 8/81 and 14/141, Standard, or Stevens 425.
Remington used the same 1:16 twist for all of their 35 Whelen rifles as well. It's plenty adequate for 250gr and more depending on bullet design. I have used up to 280gr bullets in both 35 Rem and 35 Whelen Remington rifles with the 1:16 factory twist with good results. A faster twist is needed for 300gr stuff, but that's not normally used in 35 Remington anyway.
There sure is a lot of bad information being shared in this thread.
