Any J frame holster should fit. The cylinder is slightly longer on a 357, not much though. Grips will be another story, doesn't that gun come with rubber combat grips. Get holsters for the 357 J frame as opposed to SP101 holster. The latter I understand has a beefier frame all the way around.
Ooops I missed the 6 shot part, nope that frame is probably closer to a K Frame than the J Frame. The SP101 is a 5 shot, as is the J Frame. Colt detective is a small frame six shot, I believe the Rossi are copies of S&W so I am betting K frame.