Hi Melissa.
If the muslin is the same weight and hand as the rest of the repros, it'd probably be okay, but I think I'd go with Bella Natural or Kona Cream if at all possible if you want to stick with the cream color. Take a look at Marcus Brothers Centennial Solids for other color options for the CW period, too. They run about $7.00 per yard and are excellent quality.
http://www.marcusfabrics.com/cgi-bin...gi?Category=22