Larry, because the doors are SO heavy and throw off the balance, I lower the body down onto jack stands and then install doors. That keeps the body stable, and I can also open the doors if I want to. Also, by placing the rear stands in the position the pictures show, it prevents the back of the body from trying to sag. All of this helps with getting the body lines straight if filler work is being done. It also keeps things square if a quarter panel has to be cut out and replaced.
I've done quite a few 'Cuda convertibles and have found that they are so weak in the lower cowl, it takes very little weight or stress to alter the door to quarter/rocker fit.
In fact, I won't even final fit the doors or install front fenders until the convertible top is installed. When the new top is latched, it pulls back on the windshield frame so hard it usually pulls the upper cowl and doors back a fraction of an inch.