How big of a cam can I throw in?

I am building a 5.9 magnum for my 1965 Barracuda. I am trying to figure out how big of a cam can I install without changing out rocker arms and push rods? I have already gotten installed the Hughes kit 1110 springs and retainers. I was recommended the Hughes cam ser1418ALN-10 they call the "steam roller" SB HYD RLR CAM 214/218 -110ÂșLSA NEW CORE but didn't want to short change myself? I also thought it might be designed for a truck type application? Advise on other cam companies or the above cam would be awesome. Just about to pull the trigger on a cam so thought I would throw my question out to the experts.

I measured this once. Details are in this thread, post #18:
How fast can you go with a Magnum? Who has the quickest setup?