You've seen my build thread, I have the Magnum 5.9.
A truck with a stock computer would different, I have the big book on Magnum rebuilds from Larry Shepard. Tomorrow I'll flip through it and get some numbers for the biggest cam the stock stuff will work with. The R/T cam comes to mind.
For the 46RH mods head here:
http://www.dodgetalk.com/forums/showthread.php?t=184663