I've had good results with a Final Strut .650 in my SBEII. High 180s to 190s with XRHD 5s, just over 200 with XRHD 6s, mid 200s with Magnum Blend and just over 300 with Hevi 7s. Also shot Federal Heavyweight 6s and 7s, they shot well but can't recall the pellet counts. All shells were 3 1/2.
I tried a .655 first, whish is the choke that Rob has found to perforn best with HTL shot and Benellis. It was also a good performer and would kill turkeys all day long, but the tighter .650 was the ticket in my gun.