"It is fairly solid but I plan to replace most of the sheet metal as I plan to keep the care for many years. I am definitely replacing the floor pans, complete cowl, firewall, radiator support, front frame rails, and quarters. This is my first restoration project and I’m not sure which area to begin with to ensure an easier transition from area to area. Any thoughts or advice would be appreciated. Thanks."
Welcome to the Mustang community.. I will make some comments from over 50 years experience restoring vehicles. Your comment "fairly solid", does not match up with what you want to replace. As others said if it doesn't need replacement don't, if it is full of rust holes and not structurally sound then you might have to. I do not know your level of experience or what tools and shop environment you have, but what you have listed is not for the inexperienced, you can get over your head pretty fast on a project such as this. Think welders (gas, MIG,TIG,) level surface, cutting tools, hydraulic push/pull equipment, body work tools, stabilizing bars to keep square and alignment, before you start etc. In reality if it really needed all of what you have listed I would pass on it, and bail out by selling what you have, and here is the reason. Being a coupe, unless you are in love with the body design, if you ever want to sell it (I know that everybody starts a project with the thought of keeping it forever) you are at the bottom of the ladder in Classic Mustang value. According to the auctions and my personal experience restoring and selling them the Fastback is King followed by the convertible. On any restoration it is easy to get upside down on value, especially on a coupe, the exception might be if it is a K code and documented GT, and even then you have to be careful. I am not trying to dissuade you just trying to educate you on what a project like this entails. I might be completely off base with my comments, and you might have everything available both skills and tools to do the work, but if you were my son and asked about diving into a project that needs everything you listed I would say lets look for a solid southern or dry area body and start from there. Either way best of luck.