Dub isn't making any more big case .60s, if I correctly understood my conversation with him. If this is correct, you may be locked into the Rossi anyway (not really a bad thing, IMO).

I have an SJ .60 (.61?) that I am installing in a H9 P7. With the Jett muffler, the total weight is about 26 oz. but it turns an APC 11x7 at 13,500 easily.
One of my friends has an SJ .60 on a Compensator-like SPA model and his is plenty fast on an APC 12x6, but I don't know the rpm.

The Rossi .60 with the VP mods should be in the SJ 60 performance range, and would be OK without the VP mods. My old Rossi 65 turns an APC 10x8 at 14000 open face, don't remember the numbers for the 11x7.

Jim