recommended cam for a 5.9 magnum?

Call Brian at IMM.

He can get you a custom cut comp for same or less than most shelf grinds.

Don't sweat the nitrous if you run it with using some common sense

yeah i'm not too worried about the N20. I don't plan to run some massive shot.(likely 125 at the very very most) and i'm gonna get it setup and make sure its tuned accordingly at a dyno shop.