Aluminum or Stainless Steel 375

You'll be fine. When you say must, I'm buttuming that your talking about mead and other wild wines as grape must doesn't need to be heated. Charlie Papazian has given aluminum pots a blessing saying that even large breweries tend to use copper material and that like copper, aluminum tends to heat more evenly. I do recommend, however, that you get an acid blend, fill your aluminum pot up with water, put in the blend then bring to a boil. It will likely darken the aluminum from oxidation. Don't scrub this off as shiny aluminum is not what you want. You want this protective layer of oxidation. Then you can relax and have a homebrew.

Also, keep in mind that many brewers will freak out if you say you use aluminum or copper, yet they'll boil thier copper wort chillers in their wort to sanitize it for a good 45 minutes including sanitizing it and using it to cool their wort. My advice to you is to disregard them and try it with a five gallon batch, then without telling them let them sample your mead, wild wine, or beer. They won't taste anything and you'll feel much more confident about it.