I would mate the coupler / adapter, install that pair to the column, and then the column to the box. I used to block the column up with pillows to get it "rough" position, then go into the engine bay and coax it together
Carefully align the master splines so you know where they are and don't have to fight them. Be careful you do not get the coupler assembled 1/2 turn off or the wheel will be upside down
I would also START by test fitting the aftermarket adapter to the box and make sure it actually fits without heavy equipment!!!
