Just a little update.
I added one of the leaves back in and I actually gained about an 1" of lift. I now have 5 leaves plus the leaf with the retainers and the overload.
I'm surprised it made that much difference. I measured before and wrote the number down, but I'm still wondering If I misread the tape. But then that would probably mean no change, and I'm not sure I'd believe that either.
Someone had asked about the wheelbase. It measures 111" with the stock front springs and the 56s installed backwards. That's center to center on the axle tubes.
I have decided I'm definitely keeping the rear axle where it is now. I'm going to do some body work and hopefully come out with something like this: