There is a huge thread on this topic that has been moved to "The Dump". Why?
I didn't have time to go through the entire thread, but I immediately noticed that the duration used for the calc was the wrong duration.
The only way to figure DCR is by using the duration where the intake valve is effectively closed, which is the "seat-to-seat" duration, AKA, "advertised" duration. Comp Cams uses duration at .015" valve lift, and sometimes .012 amd .010 as well. This is known in the SAE as J604d duration, which is duration at .006" valve lift.
Was this ever addressed in the thread?