I've read about people going as high as 6500-7000 stock rockers, not sure about cam profiles on them, David Barton has gone over 8k but I have no clue as to cam and rockers.
I have a kid who works for me here that has a 06 magnum, 392 inch 5.7 , 4 in bore 3.9 stroke , Eagle heads runs a RLD- H5 cam Lift is 605/.611, stock rockers ,I've personally seen hit 7200 ,now he's running a set of PRW PQX steel rockers and is turning up to 7500.
I think the crank is more of an issue then valve gear from some of the things I've read here on moparts

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