Imposing two up head-to-head art the easy wat

I am working on a box set up on a two-up, head-to-head sheet. I've attached the template I'm working from. I nearly have the bottom box completed and I'd almost bet the farm that there's a way to take my completed bottom and impose over the top part of the template in one fell swoop --- but of course, I don't have a clue what that might be.

Any and all advice is appreciated.

Thanks to those who know more than me,
Joe