I believe if you go with the 6.4 cam, you also need different springs and pushrods due to the lift. Also I would go with hellcat lifters as they are pretty beefy compared to stock older versions. Maybe someone can correct me if I'm wrong but I read somewhere that dodge used msd lifters in older engines but were never activated. I haven't tore into a older block to see the lifters myself to verify this but something I read somewhere.
