I'd be careful in picking one for a 440 to run in a 383. sure it will fit and probably not have piston to valve problems, but the duration is designed to do what they say it will do, with the cubic inches that it has to work with. a larger cubic inch motor can take more duration and maintain the street-ability they proclaim.
put one into a 383 and the power band will move up in the RPM range to the point that it might not work all that well on the street without huge stall and gears.

if you're considering running the RB cam in a B motor...contact them and ask them what they think, and what they recommend that you do to make it work--stall, gears, etc.