The problem with finish line, or at least the finish lines ive been to, is that the tees they have do go up to 4 XL but they are not tall at all. Basically they are made for fat people not for skinny tall people.
Instead of just getting 4XL tees that are wide as hell, make sure to get your tall-ts in a big and tall section at a department store or online. They will usually be marked as 2XLT, 3XLT, and so on. Personally, I went to Marshalls and got a super tall white tee for 6 bucks in the big and tall section. They fit much better to your body but are still tall as hell