I am constructing rotisserie brackets for my 68. I found an individuals reference for a 1st generation mustang that mentions a 9" drop from the center of the rotation pivot center to the center of the front bumper bracket mounting holes on the chassis and maybe close to the same height or no drop on the rear bumper mounting holes.

Its possibly the same as the mustang. Anyone worked out the drop in inches needed to balance the pivot on the cougar? thanks

I always attached the brackets to the same holes that the front and rear bumpers bolt to, and had no problems with being off balance.

I started this one by modifying harbor freight 1K engine stands and 3 ton lift jacks.

It looks like the amount of stuff left on the car comes into play. Mustang loaded with everything, the distance is close to center
Cougar striped to the chassis is further away for the center pivot to get rotational balance
I was going to make both front and back body brackets fixed, but will try to work out a way to adjust the front using the materials I have available.

Mine grabs the front frame rails where the bumper mounts. Center point is at the middle of the grille with a bare body shell. The center changes as parts are added/subtracted. The rear center is just below the gas filled hole. I made brackets that come down off the frame rail as that is much stronger then using the rear bumper mounting holes. Whatever you make you need the option to adjust the center. Especially if you plan on using different car bodies.