crosswind air gap or stock 4bbl manifold

The .050 duration has nothing , absolutely nothing, to do with calculating Dcr. Only the ICA matters, along with several other specs,such as; the true Measured Static cr, rod length, and boreNstroke. In this case the 270 adv duration and the 114LDA translate to an ICA of about 69* depending on where you install it. In this example,I chose to install at 114*CL.
If the posted specs are correct, this cam has some very looong ramps.( 270 - 204)/2 = a 33* ramp.. I have a hughes fast rate cam that is published as a 232*@.050, and is only a 276 advertised IIRC. (276 - 232)/2 =a 22*ramp. So for nearly the same advertised duration, my cam is 232 - 204 = 28 * bigger. Thats about 4 cam sizes or better. My cam will idle like the OPs, but make peak power some 800 to 1000rpm higher. The extra rpm builds mathematical or theoretical horsepower.Let it breath, and it becomes real.
Those 050 cam specs sound very familiar.Isn't that just a tad bigger than a 360-2bbl cam?