If you want something that is still in production that should fly similar, try the Cosmic Wind Minnow.

http://www3.towerhobbies.com/cgi-bin...?&I=LXKAG2&P=0

Both the shoestring and the Cosmic Wind Minnow were Pylon (Reno) racers, and both being shoulder wing aircraft should have similar flight characteristics.

Minnow has larger wingspan and more wing area so it will be a little slower on landings, and maybe a little less agile than the Shoestring.