I gather you're aiming for fuel mileage.......
At the expense of everything else,
including passing and hill-climbing.
Separating the intake and exhaust events to such a radical degree, may get you mpg on hard level and flat ground, under steady state cruising, from point to point, but this does not take into account the real world terrain and driving circumstances.
IMO, you'll be hard pressed to improve on the 5.2s design for your application.
But if you were willing to upgrade to a 5.9, well then, that could be modded to better suit your application.
Oh, no,:( it too is already set up just right for your application. But the good news is the 360Magnum was born with mega torque.
About all you can do with the 5.9 is to de-cam it to a 5.2 cam, but the compression ratio would also have to come down.IMO hardly worth the expense.
What I mean by that is the pay-back period in fuel savings would be measured in years.
