I don't know what model the SBL is, but my SS handles cast bullets very well. The vast majority of what I shoot is cast, with most of those being the Lee 405gr hollow base bullet.
I load fairly mildly, using 15.0gr of Unique, which gives around 1100-1200 fps, if I remember correctly. As I stated earlier, these are almost one-hole accurate at 50yds, and easily 1.5" at 100yds. This is a very inexpensive load to shoot, and is easy on the shoulder. I imagine it would drop any deer that walked, out to maybe 200yds or better, if you could dope the trajectory.
I am hoping to get to try that load on deer and hogs this year, but time is beginning to run out on the deer part of it.
I also cast the Ranch Dog 360gr gas-checked bullet, but haven't done a lot of load development with it yet.
The 45-70 is just a natural with cast bullets..
I always felt that if I got to the point where I thought it was time to bury my firearms, it was actually time to pick them up..