Great box but I'm WAYYYYYYYY to "cheap" for that.
My two cents says (& what I run) are to find a good box from a 73 to 77 GM "A" body (malibu/cutlass/monte/regal) that is a 4 bolt mount. Darn close to a drop in. Only thing you will have to do from there is to change the fitting in the back of your P/S pump to a flange from and O-ring. (you can get it out of the same car and screws right in the back of the pump)
And while you're at it.........get a pump off a chevy one ton with hydroboost brakes. (73-91) The extra pressure makes bigger tires a one finger turn on the wheel.
At least thats what I did.