AMBIGRAMS. Ambigrams are dope. The 6 on this die is a simple one - upside down, it looks like a 9, as a six is wont to do. To get higher than 87, we need more of these.
If we add more ambigrams, we can fit more numbers. The first is either a 4 or a 7, and the second a 2 or 3, depending on orientation. So, consider these dice:
[0, 1, 2/3, 4/7, 5, 6/9]...