Dark---
I ran the .474 280 on a 440 a few years back, even got a best of 13.1 in a low compression 3500 lb cuda, thats not bad.
BUT, Compare it to my current cam--the 60303 Lunati that is a .494/.513 (if memory serves) and approx 268/272 degrees. Thats significantly more lift with a little less duration, meaning the cam is snapping the valves open and closed MUCH faster. That gives you significantly better breathing (and we all know its all about maximizing airflow) since the when the valves are open they are OPEN (and closed for that matter)
Thats old school vs. modern grinds. Duration doesn't make power--LIFT does (again airflow).
You've got those wonderfully fat lifters--use em!