The term chain in this case usually refers to the measuring instrument rather than a unit of length; the distances measured with such an instrument are normally measured in feet (and usually decimal fractions of a foot, not inches).
Messages: 7,549. Likes Received: 4,600. For the record, Disney did try to sell lifetime passes at the Magic Kingdom the first year it was open (1971) called a Gold Pass for $100. This pass was said to be good for a lifetime and for any additional parks that they may add in the future.
Most of the rides at Walt Disney World have no height requirement. However, for the safety of guests there are height requirements for some attractions. These height requirements vary widely; the requirement could be anywhere from 40 to 52 depending on the ride. You can find a complete list of height requirements on the WDW website.