http://www.vintage-trek.com/Trek-Fis...nualLemond.pdf
Look at the Zurich geometry in the manual from the above link. Lemonds generally have a longer top tube and the fit is considered on the large side. The sizing on this model is listed as 51cm and 53cm, not 54. At 5'6", depending on your body dimensions, the 54 might be a bit big for you, but doable. Is the seller close enough for you to go and visually check out the bike, or someone you know close enough? Those frames and forks are really nice and, it it fits you, quite comfortable. Buying a bike unseen and without a test ride is always a bit of a gamble. You almost always have to put some money into one to fix or change out components/parts. If you can do that yourself, the cost is minimized.