I would run the 4.56... doing some calculations you
wouldnt even be at 7000...6400 + the conv, so if your
conv has 5% slippage thats basically 6750 rpm running
low 10s.... JMO but I like to see about 1500 rpm
between the conv flash and the gear change and set
the conv to flash at about max torque or a couple
hundred rpm above max torque