My 49 3100 w/216 has a Rochester model B and it works pretty good. Starts, idles and excelerates smoothly.
I especially like the step cam that slightly increases idle rpm when the choke is closed to partially closed.
One thing I've found out thus far is it didn't like the late model paper element I installed in the air cleaner. It was too restrictive. I went back to the original mesh filter and it worked much better. I'm thinking of hunting down an OEM oil bath.
Good luck
Dave