I've run both single and dual Rochester's on a 235 with overdrive getting near 20 mph. They seem OK to me but then again I've never run anything else. As far as leaks go I ride an old Harley so I wouldn't notice something like that.
I am putting a 261 in soon (this weekend I hope) and have given some thought to switching to a pair of Rochesters from a 216 instead of the ones from a 235. I already milled the bases to fit my manifold. Any thoughts?