Are there any improvements that you plan to do with insulation I attic or walls?
I did note that you have vinyl windows already so adding some insualtion to the attic is very cost effective and will help on the load on the home.
I will give my home as example for base comparaion since I can't see your home. My home was built in 1978 and I have owned it for 12 years. 1784 heated square foot. When I first purchased it had double metal windows and (3.5) ton unit.
Fast forward to now and I have changed out windows to double vinyl and added add. Insulation to the attic. Now per manual j I have a (2.5) ton Trane system installed and it works like a champ with electric bills no higher then $100.00....
While my home is not yours I live in the same region you do which is northeast la.. Our design temp for summer is 95 degrees. I would be willing to beat that your home as it sets today does not need a (3.5) ton system but since I have not ran a load I can't say that's it is acrate sized.
So how guess the request for a load cal. Or have they come up with excuses not to run one?