Spark Plugs On A Magnum Crate Motor?

Plugs are matched to engine head style and compressions ratio and intended usage. As far as the 408 you got with the Champion C59yc in it it's possible it's right If it matches the criteria of what is needed for the engine. If your not sure your best bet is to call Champion or whatever brand plugs you want to use and tell them your combination and ask for their suggestion.