Draw length is 28 inches.
If I remember, that bow has a sharp recurve.
A string which fits loosely over the knocks in a straight line across the front (not stringing it) should be about right. If you can't find one exactly, go up to the next size.

If there is not archery shop near you, call Three Rivers Archery or Jeffery Archery. They will have lots of strings and a chart matching them to old bows.