I made that outfit for a child once. I used Simplicity 4669. I used a medium weight fabric and modified the heck out of the pattern. Luckly I had some dress blues to study. The belt was two belts from the Salvation Army; I think I used velcro because of time. Don't worry the pocket sounds more complicated then it is. The difficult part for me was finding the ribbon bar and stars for the shoulders. I think I just ended up modifying a pin I had and wrapped it in red, white and blue grosgrain ribbon. The stars where buttons. If you have an army surplus near you check them out of the trimmings. I hope this helps.
Also, double check your pattern. I want to say old ones run smaller around the waist then modern ones.
Women and cats will do as they please. Men and dogs had better get used to it.