(2)450 DP's vs (2)750 DP's

TT5.9mag said
Yes it will, but look how rich you are at low rpm, so lean out that range, and fatten up the range (1500-3000) above it. That’s the goal.

That's interesting. I see it the other way. Idle is about normal (for pre-smog) AFR but by 30 mph its going lean and going leaner. I'd be looking to richen or extend the idle-transition so it doesn't go away so quick.