lilmodeler
First of all, welcome to the forum!
There are several brands and types of metal finishes available, and you will find just as many people here who will swear by each of them. Basically whatever works for you is what you will find the best, but it may take you a few tries of each to find that out.
For myself, I have had good luck with Model Master metal finishes, including the buffable type. I also have a bottle of Alcad II that I haven't yet tried, but Swanny swears by it.
There is also the BareMetal foil that looks awesome when it's done right, but it's too much work for me (I'm too impatient).
Give this thread a little time to get answers from the others. They are far more experienced than me.
Good luck with your Mustang, and let us know how it progresses.
stinger