Back when I was looking around for PS boxes, I recall finding that the mid-70s Dodge truck PS boxes had both standard and reverse rotations, remanufactured by 'Lares.' If you fabbed up a bracket, the reverse-rotation box ought to fit inside the frame rail like the stock unit. You'd have to use a modern steering column, but big deal. I ended up using an 'ad-on' linkage system with sensor valve on the drag-link and a hydraulic ram behind the solid front axle. I still have the original steering column with 70s steering wheel.