How To:Biggest Magnum TQ Monster
If you're going to put a cam in the 5.9, the R/T cam is a good choice. I think Crane makes it. 204/208 with lift in the .460 range IIRC (.458/.467). You do have to watch the lift with the stock mag heads.
I have this cam in my Dakota with a 5.2 with many modifications and dynoed 247 rwhp 265 rwtq with the M1 intake. A friend dynoed his 5.2 with the same cam but the stock kegger and was 215 rwhp and around 280ish on rwtq. Can only imagine this would make a 5.9 a real stump puller.
Another option if you don't want to dive into the 5.9 too much is switching from 1.6 to 1.7's rocker arms. Seen some good results from this alone.