I think this is my option. By the looks of it the rear struts go in between the rear back and the rear bottom seat and anchor to the floorboard in front of the axle hump. I want to say I have seen the cross brace from left to right be swinging in and out with a quick-fastener so you can get passengers in the rear but I rarely carry passengers in the rear. My priority is two people up front

https://www.rhodesracecars.com/4-Point-Roll-Bar--68-70-CORONET-CHARGER-ROAD-RUNNER_p_8705.html