I would keep the smaller one in the acclimation box until you start seeing pairing behavior “through the glass”. Stop switching them and don’t move them around anymore.
Putting them together to fight it out is up to you, but understand that a fatality is possible. I personally would not let the two fish at each other without seeing a week or two of them acting like pair.
I’ve paired maroons twice. Both times it went relatively quickly and easily by introducing a 1” juvenile as the new fish into a tank with a mate near 3”. Both times I used a modified strawberry basket to create a refuge for the juvenile fish to escape to.
Others may chime in as you are in uncharted territory as far as my personal experience goes. Good luck and keep us posted...