According to Brian, the reasoning behind the Chevy lobe was the less aggressive valvetrain motion to handle the sustained time at RPM. Not just RPM, loaded RPM. Closer to circle track than road race or autocross.

How much of a difference is there to be had playing with LSA to optimize the 4500-6000 range? I do feel inclined to get back up to the .600 lift line with the 1.5's, but there is a healthy increase in duration that comes along with that. I'd be at 280° @ .050. to get .590".

Mopar Lobes:

#6587: Adv. 289°, 263° @ .050, Lobe lift .404, Lift w/ @ 1.5 .606
#6588: Adv. 293°, 267° @ .050, Lobe lift .411, Lift w/ @ 1.5 .617

Interesting thing I just noticed: My current 6333 with a 1.6 has .608" with 268° @ .050. Almost the same as the Mopar lobes with 1.5's.