I've seen alot of guys tighten the lash up on the 590 cam with good results but it never helped mine, it liked 28/32 in my 451 with Eddy heads and it was a 9 second bracket car. Maybe it just didn't like the extra lift since it was a mild combo with low compression.

1970 Challenger, all aluminum 528 Hemi, HDK suspension, Tremec 5 speed manual