I haven't purchased anything from them yet, but here's a link to a company that I've been considering for a new vanity because they offer lots of different sizes, styles, finishes, and choices for the top. They do a 60" double vanity in a number of different styles and wood finishes with a choice of vanity tops that includes carrara and crema marfil marble (along with different granites, etc.). It takes a while to navigate their site to see all the options, but I double checked and they have the dimensions and materials you are looking for.
http://www.strasserwood.com/index.html