408 Magnum Stroker Build...cam selection

ok magnum
but "roller rocker cam" threw me
so roller tip rockers or not?
anyway 274 HR is bigger than a 274XE
your best shot if you want that lift
stock exhaust
and shorter duration and less overlap (the 274xe sucks for that)
is to go here
Street Performance | Jones Cams
and get one his inverse profile hr grinds
He can do the same top end with 8 degrees less duration which solves your problem
no one else can do it
He's done 3 stock exhaust cams for me and they flat work