Hee hee, I have the opposite problem! I can never find pants that are long enough! I have a pair of Adidas running pants that are long enough, but very loose in the seat/waist.
There is a company in Oregon that makes running pants in a lot of sizes and colors. www.pacewear.com They might have the length and waist you need, and the colors you like.
When my Adidas finally fall apart (and/or fall off my hips) I'm planning to get a pair of Pacewear pants or Sporthills.
"If Americans want to live the American Dream, they should go to Denmark." - Richard Wilkinson