Ok - let me walk out to the detached garage and take some pictures ... My setup is B block with Edelbrock Performer RPM heads and Indy valve covers. I have a MSD Pro-Billet Distributor for RB engine in there with the Mopar Performance RB to B adapter. When I was putting this motor together, it was my first B deck motor. All my parts were RB. I never thought much about it when I put the adapter on and stabbed the distributor in. It went in without any need to grind anything. Now that you asked if it would clear, I took the picture. And it looks to me like the B version of the MSD distributor would just kiss the valve cover. For once, things went well when I used a slightly unconventional setup. I never realized this until I took the picture.

BTW - that coil mount bracket took me most of the day to whittle out of a solid block of aluminum using my drill press, belt sander and a hacksaw! After reading through this thread, maybe I'll add the HEI chip and have a one-wire ignitions setup!! Great for dyno and test stand runs!